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strtoul(), strtoull()

Convert a string into an unsigned long integer


#include <stdlib.h>

unsigned long int strtoul( const char * ptr,
                           char ** endptr,
                           int base );

unsigned long long strtoull( const char * ptr,
                             char ** endptr,
                             int base );


A pointer to the string to parse.
If this argument isn't NULL, the function stores in it a pointer to the first unrecognized character found in the string.
The base of the number being parsed:



Use the -l c option to qcc to link against this library. This library is usually included automatically.


The strtoul() function converts the string pointed to by ptr to an unsigned long; strtoull() converts the string pointed to by ptr to an unsigned long long.

These functions recognize strings that contain the following:

The conversion ends at the first unrecognized character. A pointer to that character is stored in the object endptr points to, if endptr isn't NULL.


The converted value.

If the correct value causes an overflow, the function will return ULONG_MAX||ULONGLONG_MAX and set errno to ERANGE. If base is out of range, the function returns zero and sets errno to EINVAL.


#include <stdlib.h>

int main( void )
    unsigned long int v;

    v = strtoul( "12345678", NULL, 10 );
    return EXIT_SUCCESS;


ANSI, POSIX 1003.1

Cancellation point No
Interrupt handler Yes
Signal handler Yes
Thread Yes

See also:

atoi(), atol(), errno, itoa(), ltoa(), sscanf(), strtol(), ultoa(), utoa()