vipsi - the friendly vip script interpreter

Flow control

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do … loop

while

until

exit

next

end

if … then

return

try … then

List functions: thisThis group of Vipsi command syntax: Instructions
Instructions
Glossary: Instructioninstructions modifies Flow control: if … then
Flow control: try … thenthe linear flow of program execution into Flow controlbranches Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and Flow control: do … looploops. There is also Flow control: if … then
Flow control: try … thenthe error catcher with 'Flow control: try … thentry' Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and Example Scripts: CGI Scripts
Example Scripts: Scriptsscript termination with 'Flow control: end
Shell Immediate Commands: exit, quit, endend'.

do … loop

Flow control: do … loopdo
    <statements>
Flow control: do … looploop

Flow control: do … loopdo
    Flow control: whilewhile <condition>
    Flow control: untiluntil <condition>
    Flow control: if … thenif <value> Flow control: nextnext Flow control: if … then
Flow control: try … thenthen
    Flow control: if … thenif <value> Flow control: exit
Shell Immediate Commands: exit, quit, endexit Flow control: if … then
Flow control: try … thenthen
Flow control: do … looploop

Repeat Vipsi command syntax: Statements
Glossary: Statementstatements between Flow control: do … loopdo Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and Flow control: do … looploop.

When Flow control: if … then
Flow control: try … thenthe Flow control: do … looploop is entered Operators: Make Identifier "@"at Flow control: do … loopdo nothing special happens. But when Flow control: if … then
Flow control: try … thenthe program execution reaches Flow control: do … looploop, Flow control: if … then
Flow control: try … thenthen Flow control: if … then
Flow control: try … thenthe program jumps back to Flow control: if … then
Flow control: try … thenthe matching Flow control: do … loopdo Vipsi command syntax: Instructions
Instructions
Glossary: Instructioninstruction. do-loops can be nested to any level.

e.g.:

Instructions: var
How does VScript::Value() work?: Var*&var i=1; Flow control: do … loopdo; Instructions: putput i; Flow control: whilewhile i<10; i++; Flow control: do … looploop;

while

Flow control: do … loopdo
    <statements>
    Flow control: whilewhile <condition>
    <statements>
Flow control: do … looploop

Conditionally leave Flow control: if … then
Flow control: try … thenthe Flow control: do … looploop. Flow control: if … then
Flow control: try … thenThe Flow controlcondition must be a numeric Glossary: Valuevalue. Flow control: if … then
Flow control: if … thenIf the <condition> is false (==0) Flow control: if … then
Flow control: try … thenthen Flow control: if … then
Flow control: try … thenthe Flow control: do … looploop is aborted Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and program execution resumes behind Flow control: do … looploop.

e.g.

Instructions: var
How does VScript::Value() work?: Var*&var d = List functions: dir
Instructions: dir
Shell Immediate Commands: dirdir(".")
Instructions: putput " current directory contents: ", Constants: nlnl
Instructions: var
How does VScript::Value() work?: Var*&var i=0
Flow control: do … loopdo
    Flow control: whilewhile i <= Numeric functions: countcount d
    put d.dir: fnamefname, Constants: nlnl
Flow control: do … looploop

until

Flow control: do … loopdo
    <statements>
    Flow control: untiluntil <condition>
    <statements>
Flow control: do … looploop

Conditionally leave Flow control: if … then
Flow control: try … thenthe Flow control: do … looploop. Flow control: if … then
Flow control: try … thenThe Flow controlcondition must be a numeric Glossary: Valuevalue. Flow control: if … then
Flow control: if … thenIf the <condition> is true (!=0) Flow control: if … then
Flow control: try … thenthen Flow control: if … then
Flow control: try … thenthe Flow control: do … looploop is aborted Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and program execution resumes behind Flow control: do … looploop. Tis is just Flow control: if … then
Flow control: try … thenthe same as Flow control: whilewhile, except with reverted Flow controlcondition.

e.g.

Flow control: do … loopdo
    Instructions: var
How does VScript::Value() work?: Var*&var n=""
    Instructions: putput #stdin, "gimme a Glossary: number, num_valnumber: "
    Instructions: getget n
    Flow control: untiluntil n==""     // break from Flow control: do … looploop

    n = Numeric functions: intint(Functions with varying return types: eval
Instructions: evaleval(n))

    Instructions: var
How does VScript::Value() work?: Var*&var a = 1
    Flow control: do … loopdo
        Flow control: whilewhile (a+=2) <= Numeric functions: sqrtsqrt(n)
        Flow control: untiluntil Numeric functions: fractfract(n/a) == 0
    Flow control: do … looploop
    Flow control: if … thenif a > Numeric functions: sqrtsqrt(n) Instructions: putput " is prime", Constants: nlnl
    Flow control: if … then
Flow control: try … thenelse           Instructions: putput " = ", a, " * ", n/a, Constants: nlnl
    Flow control: if … then
Flow control: try … thenthen
Flow control: do … looploop

exit

Flow control: do … loopdo
    <statements>
    Flow control: exit
Shell Immediate Commands: exit, quit, endexit
    <statements>
Flow control: do … looploop

Unconditionally leave Flow control: if … then
Flow control: try … thenthe Flow control: do … looploop. Flow control: if … then
Flow control: try … thenThe program execution resumes behind Flow control: do … looploop. Since it makes no sense otherwise, Flow control: exit
Shell Immediate Commands: exit, quit, endexit is most likely within a conditional Flow controlbranch between Flow control: if … thenif Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and Flow control: if … then
Flow control: try … thenthen.

e.g.:

Instructions: var
How does VScript::Value() work?: Var*&var i=1
Flow control: do … loopdo
    Flow control: if … thenif i>100 Flow control: exit
Shell Immediate Commands: exit, quit, endexit Flow control: if … then
Flow control: try … thenthen
    i+=i
Flow control: do … looploop
Instructions: putput "i = ", i, Constants: nlnl

next

Flow control: do … loopdo
    <statements>
    Flow control: nextnext
    <statements>
Flow control: do … looploop

Jump back to Flow control: do … loopdo Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and restart execution of Flow control: if … then
Flow control: try … thenthe Flow control: do … looploop. List functions: thisThis is just what Flow control: do … looploop Flow control: do … loopdoes, Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and since it would make no sense otherwise, Flow control: nextnext is most likely within a conditional Flow controlbranch between Flow control: if … thenif Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and Flow control: if … then
Flow control: try … thenthen.

e.g.

Instructions: var
How does VScript::Value() work?: Var*&var i=1
Flow control: do … loopdo
    i+=i
    Flow control: if … thenif i<100 Flow control: nextnext Flow control: if … then
Flow control: try … thenthen
    Flow control: exit
Shell Immediate Commands: exit, quit, endexit
    Numeric functions: log
Numeric functions: loge
Instructions: loglog "never seen"
Flow control: do … looploop
Instructions: putput "i = ", i, Constants: nlnl

end

Flow control: end
Shell Immediate Commands: exit, quit, endend
Flow control: end
Shell Immediate Commands: exit, quit, endend 0
Flow control: end
Shell Immediate Commands: exit, quit, endend 1
Flow control: end
Shell Immediate Commands: exit, quit, endend <value>

Flow control: end
Shell Immediate Commands: exit, quit, endEnd of Example Scripts: CGI Scripts
Example Scripts: Scriptsscript optionally returning a Glossary: Valuevalue.

Flow control: whileWhile Flow control: returnreturn, when executed in a Vipsi command syntax: Procedures
Data Types: Procedures
Glossary: Procedureprocedure, will only Flow control: returnreturn from Flow control: if … then
Flow control: try … thenthe Vipsi command syntax: Procedures
Data Types: Procedures
Glossary: Procedureprocedure, Flow control: end
Shell Immediate Commands: exit, quit, endend allways Flow control: exit
Shell Immediate Commands: exit, quit, endexits from Flow control: if … then
Flow control: try … thenthe whole Example Scripts: CGI Scripts
Example Scripts: Scriptsscript.

Flow control: end
Shell Immediate Commands: exit, quit, endend may optionall Flow control: returnreturn a Shell Scripts: Return values
Appendix: Return valuesreturn value. Whether it is expected to Flow control: do … loopdo so Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and which Glossary: Valuevalues are acceptable depends on Flow control: if … then
Flow control: try … thenthe invocation of Flow control: if … then
Flow control: try … thenthe Example Scripts: CGI Scripts
Example Scripts: Scriptsscript.

if … then

Flow control: if … thenif <condition>
    <statements>
Flow control: if … then
Flow control: try … thenthen
Flow control: if … thenif <condition>
    <statements>
Flow control: if … then
Flow control: try … thenelse
    <statements>
Flow control: if … then
Flow control: try … thenthen
Flow control: if … thenif <condition>
    <statements>
Flow control: if … thenelif <condition>
    <statements>   
[ Flow control: if … thenelif <condition>
    <statements> … ]
Flow control: if … then
Flow control: try … thenelse
    <statements>
Flow control: if … then
Flow control: try … thenthen

Execute <statements> only Flow control: if … then
Flow control: if … thenif the <condition> is true.

All Flow controlconditions must be a numeric Glossary: Valuevalues Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and are considered 'true' Flow control: if … thenif they are non-zero.

Flow control: if … then
Flow control: if … thenIf the Flow controlcondition is true, Flow control: if … then
Flow control: try … thenthen Flow control: if … then
Flow control: try … thenthe Vipsi command syntax: Statements
Glossary: Statementstatements in Flow control: if … then
Flow control: try … thenthe following Flow controlbranch are executed Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and Flow control: if … then
Flow control: try … thenthe program finally jumps to Flow control: if … then
Flow control: try … thenthe Flow control: if … then
Flow control: try … thenthen Vipsi command syntax: Statements
Glossary: Statementstatement, skipping all optionally present Flow control: if … thenelif Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and Flow control: if … then
Flow control: try … thenelse Flow controlbranches.

Flow control: if … then
Flow control: if … thenIf the Flow controlcondition is false, Flow control: if … then
Flow control: try … thenthen List functions: thisthis Flow controlbranch is skipped, Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and all optionally present Flow control: if … thenelif Flow controlconditions are tested in order. Flow control: if … then
Flow control: try … thenThe Flow controlbranch of Flow control: if … then
Flow control: try … thenthe first Flow control: if … thenelif Flow controlcondition which is true is executed Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and Flow control: if … then
Flow control: try … thenthe program finally jumps to Flow control: if … then
Flow control: try … thenthe Flow control: if … then
Flow control: try … thenthen Vipsi command syntax: Statements
Glossary: Statementstatement, skipping all other Flow control: if … thenelif Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and Flow control: if … then
Flow control: try … thenelse Flow controlbranches.

Flow control: if … thenIf all Flow controlconditions fail, Flow control: if … then
Flow control: try … thenthen Flow control: if … then
Flow control: try … thenthe final Flow control: if … then
Flow control: try … thenelse Flow controlbranch is executed, Flow control: if … thenif present. Flow control: if … thenIf no Flow control: if … then
Flow control: try … thenelse Flow controlbranch is present, Flow control: if … then
Flow control: try … thenthen actually no Vipsi command syntax: Statements
Glossary: Statementstatements between Flow control: if … thenif Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and Flow control: if … then
Flow control: try … thenthen except for Flow control: if … then
Flow control: try … thenthe Flow control: if … thenelif Vipsi command syntax: Instructions
Instructions
Glossary: Instructioninstructions are executed Operators: Make Identifier "@"at all.

e.g.

Flow control: if … thenif (a>b) Flow control: returnreturn a; Flow control: if … then
Flow control: try … thenelse Flow control: returnreturn b; Flow control: if … then
Flow control: try … thenthen;

Flow control: if … thenif a<0
    Instructions: putput "a is smaller than zero"
Flow control: if … thenelif a==0
    Instructions: putput "a is exactly zero"
Flow control: if … thenelif a>0
    Instructions: putput "a is greater than zero"
Flow control: if … then
Flow control: try … thenelse
    Instructions: putput "you caught a NaN"
Flow control: if … then
Flow control: try … thenthen

return

Flow control: returnreturn
Flow control: returnreturn <value>

Flow control: end
Shell Immediate Commands: exit, quit, endEnd Vipsi command syntax: Procedures
Data Types: Procedures
Glossary: Procedureprocedure Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and optionally Flow control: returnreturn a result Glossary: Valuevalue.

Flow control: if … thenIf a Vipsi command syntax: Procedures
Data Types: Procedures
Glossary: Procedureprocedure Flow control: returnreturns a Glossary: Valuevalue, it should be called like a Vipsi command syntax: Functions
Functions
Glossary: Functionfunction. Flow control: if … then
Flow control: try … thenThe result Glossary: Valuevalue may be any Data Types
Invariants: Data typesdata type Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and of any size.

Flow control: if … thenIf a Vipsi command syntax: Procedures
Data Types: Procedures
Glossary: Procedureprocedure Flow control: returnreturns no Glossary: Valuevalue, it should be called Operators: Make Identifier "@"at Flow control: if … then
Flow control: try … thenthe place of an Vipsi command syntax: Instructions
Instructions
Glossary: Instructioninstruction.

Flow control: if … thenIf Flow control: returnreturn is executed on 'ground level', that is, outside any Vipsi command syntax: Procedures
Data Types: Procedures
Glossary: Procedureprocedure, it Flow control: returnreturns from Flow control: if … then
Flow control: try … thenthe current Example Scripts: CGI Scripts
Example Scripts: Scriptsscript. Flow control: if … then
Flow control: try … thenThen Flow control: returnreturn behaves just like Flow control: if … then
Flow control: try … thenthe Vipsi command syntax: Instructions
Instructions
Glossary: Instructioninstruction Flow control: end
Shell Immediate Commands: exit, quit, endend. Flow control: if … then
Flow control: try … thenThe possible Shell Scripts: Return values
Appendix: Return valuesreturn value depends on Flow control: if … then
Flow control: try … thenthe invocation of Flow control: if … then
Flow control: try … thenthe Example Scripts: CGI Scripts
Example Scripts: Scriptsscript:

e.g.:

Instructions: procproc Geomed(a,b) { Flow control: returnreturn Numeric functions: sqrtsqrt(a*b); }

Instructions: procproc Check(t) { Flow control: if … thenif Numeric functions: istextistext(t) Flow control: returnreturn; Flow control: if … then
Flow control: try … thenelse Instructions: putput "no Data Types: Text
Item selector "[]": Text
Glossary: text, text_valtext:",t; Flow control: if … then
Flow control: try … thenthen }

try … then

Flow control: try … thentry
    <statements>
Flow control: if … then
Flow control: try … thenthen
Flow control: try … thentry
    <statements>
Flow control: if … then
Flow control: try … thenelse
    <statements>
Flow control: if … then
Flow control: try … thenthen

Execute Vipsi command syntax: Statements
Glossary: Statementstatements with a "safety net".

Flow control: if … thenIf a runtime error occurs, Flow control: if … then
Flow control: try … thenthen Flow control: if … then
Flow control: try … thenthe program is Operators: Bitwise Not "~"
Operators: Boolean Negation "!"not aborted with an error message. Instead Flow control: if … then
Flow control: try … thenthe program execution resumes after Flow control: if … then
Flow control: try … thenthen Operators: Boolean Or with Variable "||="
Operators: Bitwise Or with Variable "|="
Operators: Bitwise Or "|"
Operators: Boolean Or "||"or, Flow control: if … thenif present, Operators: Make Identifier "@"at your error handler after Flow control: if … then
Flow control: try … thenelse.

In case of an error Flow control: if … then
Flow control: try … thenthe Glossary: Variable, var_refvariable errorstr is created (Flow control: if … thenif it Operators: Bitwise Not "~"
Operators: Boolean Negation "!"not already Numeric functions: existsexists) Operators: Boolean And with Variable "&&="
Operators: Bitwise And with Variable "&="
Operators: Bitwise And "&"
Operators: Boolean And "&&"and contains Flow control: if … then
Flow control: try … thenthe error message.

Your error handler Instructions: getgets also called Flow control: if … then
Flow control: if … thenif the error occurs deep inside some nested Vipsi command syntax: Procedures
Data Types: Procedures
Glossary: Procedureprocedure Functions with varying return types: call
Instructions: callcall, Flow control: if … thenif no other error handler catches it before you.

e.g.:

Flow control: try … thentry
    Instructions: openinopenin #4, "that damn ol' Text functions: file
Instructions: filefile"
Flow control: if … then
Flow control: try … thenelse
    Numeric functions: log
Numeric functions: loge
Instructions: loglog "failed: ", errorstr, Constants: nlnl
Flow control: if … then
Flow control: try … thenthen

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