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Retrieve the next argument in a function's variable argument list

Note

The va_arg() function is used only within user-defined function() statements that specify a variable list of arguments in the function() definition.

Syntax

va_arg(va-list)

Parameter

Description

Th e va_arg() function returns the next argument from the variable-length list va-list. If there are no mo re arguments in va-list, t he va_arg() function returns the NULL string and sets the PSL variable errno = 69 (E_PSL_ERANGE). 

When used with the va_start() function, the va_arg() can read a variable argument list multiple times, using the va_start() function to reset the list after each reading. (The va_start() function always resets the variable argument list to return the first argument.)

Example

The following is an exam ple of the va_arg() functio n:

function summation(...) { c = sum = 0; terms = va_start(); c = va_arg(terms); while (c != "") { sum += c; c = va_arg(terms); } return sum; } function main() { print("Sum of the first 2 numbers is : ",summation(1,2),"\n"); print("Sum of the first 3 numbers is : ",summation(1,2,3),"\n"); print("Sum of the first 4 numbers is : ",summation(1,2,3,4),"\n"); print("Sum of the first 5 numbers is : ",summation(1,2,3,4,5),"\n"); print("Sum of the first 6 numbers is : ",summation(1,2,3,4,5,6),"\n"); print("Sum of the first 7 numbers is : ",summation(1,2,3,4,5,6,7),"\n"); print("Sum of the first 8 numbers is : ",summation(1,2,3,4,5,6,7,8),"\n"); print("Sum of the first 9 numbers is : ",summation(1,2,3,4,5,6,7,8,9),"\n"); return; }

The example produces the following output:

Sum of the first 2 numbers is : 3.000000 Sum of the first 3 numbers is : 6.000000 Sum of the first 4 numbers is : 10.000000 Sum of the first 5 numbers is : 15.000000 Sum of the first 6 numbers is : 21.000000 Sum of the first 7 numbers is : 28.000000 Sum of the first 8 numbers is : 36.000000 Sum of the first 9 numbers is : 45.000000

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