June 4, 1993 ATOI 3

### NAME

atoi - convert ASCII string to integer

### LIBRARY

Standard C Library (libc, -lc)

### SYNOPSIS

```int` atoi(```const char *nptr`)

### DESCRIPTION

The atoi(``) function converts the initial portion of the string pointed to by nptr to integer representation.

It is equivalent to:

  `

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

  `

### SEE ALSO

atof(3), atol(3), strtod(3), strtol(3), strtoul(3)

### STANDARDS

The atoi(``) function conforms to ANSI X3.159-1989 (``ANSI C89'') .

### CAVEATS

atoi does no overflow checking, handles unsigned numbers poorly, and handles strings containing trailing extra characters (like ``123abc'') poorly. Careful use of strtol(3) and strtoul(3) can alleviate these problems.