My string filling function in C not working?

Question

I tried to do it myself, but failed (I am tempted to do it again for training, but I just need it as an example). Essentially, I want to represent a binary number, but of course with the closest byte to 0, so I found a function on a different issue here:

char * string_pad(char * string, size_t padlen, char * pad) {
    size_t lenstring = strlen(string);
    size_t lenpad = strlen(pad);

    char * padded = (char*)malloc(lenstring + lenpad + 1);
    strncpy(padded, string, lenstring); /* copy without '\0' */
    padded += lenstring; /* prepare for first append of pad */
    for(padlen += 1; padlen > 0; padlen--, padded += lenpad)
        strncpy(padded, pad, lenpad);
    *padded = '\0';
    return padded;
}

I call it this way:

printf("Test: %s\n", string_pad(dec2bin(~myInt), 32, "0"));

Unfortunately, he prints "Test:", but nothing more. Mine dec2binreturns a simple char pointer if you need to know.

What seems to make him do nothing?

Why does this function accept a char * panel, not a char panel, so I can just put it with "0", will "0" work or will it add a null terminator, twisting it or something like that?

. - ( ), ? .

chararray, , , , .

Answer 1

"padded" , .

Answer 2

. , .

char *PadLeft(char *bufBeg, size_t bufSize, char padChar)
{
    char *p = bufBeg;
    char *end = bufBeg + bufSize;

    while (p < end && isspace(*p))
    {
         *p = padChar;
         p++;
    }

    return bufBeg;
}

...

char padArea[32 + 1];

snprintf(padArea, sizeof(padArea), "%*s", sizeof(padArea) - 1, dec2bin(~myInt));

PadLeft(padArea, sizeof(padArea), '0');
...

... ...

int padAreaSize = 32 + 1;

char *padArea = malloc(padAreaSize);

snprintf(padArea, padAreaSize, "%*s", padAreaSize - 1, dec2bin(~myInt));

PadLeft(padArea, padAreaSize, '0');

...

free(padArea);

( , )

:

char *PadRight(char *bufBeg, size_t bufSize, char padChar)
{
    char *p = bufBeg + bufSize;

    while (--p >= bufBeg && isspace(*p))
    {
         *p = padChar;        
    }

    return bufBeg;
}

int padAreaSize = 32 + 1;

char *padArea = malloc(padAreaSize);

snprintf(padArea, padAreaSize, "%-*s", padAreaSize - 1, dec2bin(~myInt));

PadRight(padArea, padAreaSize, '0');

...

free(padArea);