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itoa() and uitoa() in Redlib

itoa() is non-standard library function which is provided in many other toolchains to convert an integer to a string. To ease porting, the Code Red IDE v4.20 and later provide two variants of this function in the Redlib C library....

char * itoa(int value, char *vstring, unsigned int base);
char * uitoa(unsigned int value, char *vstring, unsigned int base);

which can be accessed via the system header....

#include <stdlib.h>

itoa() converts an integer value to a null-terminated string using the specified base and stores the result in the array pointed to by the vstring parameter. base can take any value between 2 and 16; where 2 = binary, 8 = octal, 10 = decimal and 16 = hexidecimal.

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

The return value to the function is a pointer to the resulting null-terminated string, the same as parameter vstring.

uitoa() is similar but treats the input value as unsigned in all cases.

Note that the caller is responsible for reserving space for the output character array - the recommended length is 33, which is long enough to contain any possible value regardless of the base used.

Standards compliance

As noted above, itoa() / uito() are not standard C library functions. A standard-compliant alternative for some cases may be to use sprintf():

    sprintf(vstring,"%d",value); // convert to decimal
    sprintf(vstring,"%x",value); // convert to hexadecimal
    sprintf(vstring,"%o",value); // convert to octal


  1. In Code Red IDE v4 prior to release v4.20, only the function itoa() was provided, though in fact this actually provided the functionality of uitoa(). The function declaration for this was:

      void itoa(unsigned int value, char *vstring, unsigned int base);

  1. The Redlib C library shipped in the Code Red IDE v3 (and earlier) did not provide implementations of itoa() / uitoa().

  2. The Newlib C library does not provide implementations of itoa() / uitoa().

redlib_itoa (last edited 2012-03-01 06:12:39 by CrSupportAb)