atoi

Interface

#include <stdlib.h>
int 
atoi (const char *nptr)

#include <xlocale.h>
int 
atoi_l (const char *nptr, locale_t loc)

Description

(int)strtol(nptr, (char **)NULL, 10);

• an optional string of tabs and spaces
• an optional sign
• a string of digits

Example 1

#include <stdlib.h>
#include <stdio.h>
 
int main(void)
{
  char *str = "123456";
  int n = atoi(str);
  printf("The string %s as an integer is = %d\n",str,n);
 
  char *str2 = "314hello";
  n = atoi(str2);
  printf("The string %s as an integer is = %d\n",str2,n);
 
  return 0;
}

Output:

The string 123456 as an integer is = 123456
The string 314hello as an integer is = 314

Implementation Notes

• The atoi function is not thread-safe and also not async-cancel safe.
• The atoi function has been deprecated by strtol and should not be used in new code.

Errors

See Also

Standards

Compatibility