Itoa

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The correct title of this article is itoa. The initial letter is shown capitalized due to technical restrictions.

The itoa function is a widespread, but non-standard function of some libraries written in the C programming language. As such, it cannot be portably used, as it is not defined in any of the C language standards.

itoa(int integer, char *string, int radix)

Where integer is the integer in which a number resides, string is the string, represented by an array of characters and radix is the base number in which the number will be represented, ranging from base 2 to 36

For the common use of converting a number to a string in base 10, a better alternative way is to use the standard function sprintf:

sprintf(string, "%d", integer);

1 History
2 Example
3 See also
4 External links

[edit] History

In the 6th edition Unix reference manual, a tutorial on the C programming language existed. It is made available here by Dennis Ritchie, C's creator. It references a function ftoa, which does what itoa does but for floats. This is the first reference to a function of its kind. However, it is not implemented, only said to be in the compiler's library.

The function itoa first appeared in the book The C Programming Language as an implementation. This may be where it may have been popularized.

[edit] Example

Following is an example C program explaining a program using itoa.

/* itoa example in C */
#include <stdio.h>                      // Standard input/output header file, needed printf and scanf
#include <stdlib.h>                     // This header file contains the itoa function

int main(void)                          // The main program function
{
  int i;                                // The variable where the number will be stored
  char buffer [50];                     // The string where converted integer will be stored

  printf ("Enter a number: ");          // Ask the user for a number
  scanf ("%d",&i);                      // And store it in the variable 'i'

  itoa (i,buffer,10);                   // Convert the integer to a base ten string
  printf ("decimal: %s\n",buffer);      // And print it on the screen

  itoa (i,buffer,16);
  printf ("hexadecimal: %s\n",buffer);  // Same here, only hexadecimal

  itoa (i,buffer,2);                    // In binary
  printf ("binary: %s\n",buffer);

  return 0;                             // Terminate the program
}