Converting int to char in C

Question

Right now I am trying to convert an int to a char in C programming. After doing research, I found that I should be able to do it like this:

int value = 10;
c         


        

Answer 1

Converting Int to Char

I take it that OP wants more that just a 1 digit conversion as radix was supplied.

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To convert an int into a string, (not just 1 char) there is the sprintf(buf, "%d", value) approach.

To do so to any radix, string management becomes an issue as well as dealing the corner case of INT_MIN

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The following C99 solution returns a char* whose lifetime is valid to the end of the block. It does so by providing a compound literal via the macro.

#include 
#include 
#include 

// Maximum buffer size needed
#define ITOA_BASE_N (sizeof(unsigned)*CHAR_BIT + 2)

char *itoa_base(char *s, int x, int base) {
  s += ITOA_BASE_N - 1;
  *s = '\0';
  if (base >= 2 && base <= 36) {
    int x0 = x;
    do {
      *(--s) = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"[abs(x % base)];
      x /= base;
    } while (x);
    if (x0 < 0) {
      *(--s) = '-';
    }
  }
  return s;
}

#define TO_BASE(x,b) itoa_base((char [ITOA_BASE_N]){0} , (x), (b))

Sample usage and tests

void test(int x) {
  printf("base10:% 11d base2:%35s  base36:%7s ", x, TO_BASE(x, 2), TO_BASE(x, 36));
  printf("%ld\n", strtol(TO_BASE(x, 36), NULL, 36));
}

int main(void) {
  test(0);
  test(-1);
  test(42);
  test(INT_MAX);
  test(-INT_MAX);
  test(INT_MIN);
}

Output

base10:          0 base2:                                  0  base36:      0 0
base10:         -1 base2:                                 -1  base36:     -1 -1
base10:         42 base2:                             101010  base36:     16 42
base10: 2147483647 base2:    1111111111111111111111111111111  base36: ZIK0ZJ 2147483647
base10:-2147483647 base2:   -1111111111111111111111111111111  base36:-ZIK0ZJ -2147483647
base10:-2147483648 base2:  -10000000000000000000000000000000  base36:-ZIK0ZK -2147483648

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Ref How to use compound literals to fprintf() multiple formatted numbers with arbitrary bases?