itoa


function
<stdlib.h>
char *  itoa ( int value, char * str, int base );

Convert integer to string (non-standard function)

Converts an integer value to a null-terminated string using the specified base and stores the result in the array given by str parameter.

If base is 10 and value is negative, the resulting string is preceded with a minus sign (-). With any other base, value is always considered unsigned.

str should be an array long enough to contain any possible value: (sizeof(int)*8+1) for radix=2, i.e. 17 bytes in 16-bits platforms and 33 in 32-bits platforms.

Parameters

value
Value to be converted to a string.
str
Array in memory where to store the resulting null-terminated string.
base
Numerical base used to represent the value as a string, between 2 and 36, where 10 means decimal base, 16 hexadecimal, 8 octal, and 2 binary.


Return Value

A pointer to the resulting null-terminated string, same as parameter str.

Portability

This function is not defined in ANSI-C and is not part of C++, but is supported by some compilers.

A standard-compliant alternative for some cases may be sprintf:
  • sprintf(str,"%d",value) converts to decimal base.
  • sprintf(str,"%x",value) converts to hexadecimal base.
  • sprintf(str,"%o",value) converts to octal base.


Example

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
 
/* itoa example */
#include <stdio.h>
#include <stdlib.h>

int main ()
{
  int i;
  char buffer [33];
  printf ("Enter a number: ");
  scanf ("%d",&i);
  itoa (i,buffer,10);
  printf ("decimal: %s\n",buffer);
  itoa (i,buffer,16);
  printf ("hexadecimal: %s\n",buffer);
  itoa (i,buffer,2);
  printf ("binary: %s\n",buffer);
  return 0;
}


Output:
Enter a number: 1750
decimal: 1750
hexadecimal: 6d6
binary: 11011010110


See also

sprintf Write formatted data to string (function)
atoi Convert string to integer (function)
atol Convert string to long integer (function)