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vprintf - Formatted output to the standard output
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Definition | #include <stdio.h> int vprintf(const char *format, va_list arg); vprintf is similar to the printf function except that, unlike printf , vprintf permits the output of arguments whose number and data types are not known at compilation time.
vprintf is used within functions to which the caller can pass a different format string and different arguments for output each time. The formal parameter list of the function definition provides for a format string format and a variable argument list ", ..." for this purpose. format is a format string as described under printf with ANSI functionality (see printf ). vprintf successively steps through an argument list arg using internal va_arg calls and writes the arguments according to format string format on the standard output stdout . The variable argument list arg must be initialized with the va_start macro before vprintf is called. |
Return val. | Number of characters output |
| if successful. |
Integer< 0 | if an error occurs. |
Notes | vprintf always starts with the first argument in the variable argument list. It is possible to start output from any particular argument by issuing the appropriate number of va_arg calls before calling the vprintf function. Each va_arg call advances the position in the argument list by one argument. vprintf does not call the va_end macro. Since vprintf uses the va_arg macro, the value of arg is undefined on return. The following applies in the case of text files with SAM access mode and variable record length for which a maximum record length is also specified: When the specification
split=no was entered for fopen , records which are longer than the maximum record length are truncated to the maximum record length when they are written. By default or with the specification split=yes , these records are split into multiple records. If a record has precisely the maximum record length, a record of the length zero is written after it. |
Example See also | See under vfprintf vfprintf, vsprintf, vsnprintf |