C <stdio.h> - sscanf() Function

The C <stdio.h> sscanf() function reads data from null-terminated character string (C string) buffer, interprets it according to parameter format and stores the results into the locations pointed by the additional arguments.

The additional arguments should point to already allocated objects of the type specified by their corresponding format specifier within the format string.

Syntax

int sscanf ( const char* buffer, const char * format, ... );

Parameters

Return Value

Returns number of receiving arguments successfully assigned (which may be zero in case a matching failure occurred before the first receiving argument was assigned), or EOF if input failure occurs before the first receiving argument was assigned.

If a reading error happens or the end-of-file is reached while reading, the proper indicator is set (feof() or ferror()). And, if either happens before any data could be successfully read, EOF is returned.

If a multibyte character encoding error occurs while interpreting wide characters, errno is set to EILSEQ.

Example: sscanf() example

The example below shows the usage of sscanf() function.

#include <stdio.h>
 
int main (){
  char mystr [] = "John  25  3000";
  char name [20];
  int age, salary;

  sscanf(mystr, "%s %i %i", name, &age, &salary);
  printf("%s is %i years old and earns %i dollars.\n", name, age, salary);

  return 0;
}

The output of the above code will be:

John is 25 years old and earns 3000 dollars.

Example: using * sub-specifier

Consider one more example where sub-specifier * is used to ignore the data while using this function.

#include <stdio.h>
 
int main (){
  char mystr [] = "John => 25 => 3000";
  char name [20];
  int age, salary;

  sscanf(mystr, "%s %*s %i %*s %i", name, &age, &salary);
  printf("%s is %i years old and earns %i dollars.\n", name, age, salary);

  return 0;
}

The output of the above code will be:

John is 25 years old and earns 3000 dollars.

Length sub-specifier

See <cinttypes> for the specifiers for extended types.