Decimal to binary Conversion of a String in C

    #include <stdio.h>
    #include <stdlib.h>
    char *decimal_to_binary(int);
    main()
    {
    int n, c, k;
    char *pointer;
    printf("Enter an integer in decimal number system\n");
    scanf("%d",&n);
    pointer = decimal_to_binary(n);
    printf("Binary string of %d is: %s\n", n, t);
    free(pointer);
    return 0;
    }
    char *decimal_to_binary(int n)
    {
    int c, d, count;
    char *pointer;
    count = 0;
    pointer = (char*)malloc(32+1);
    if ( pointer == NULL )
    exit(EXIT_FAILURE);
    for ( c = 31 ; c >= 0 ; c-- )
    {
    d = n >> c;
    if ( d & 1 )
    *(pointer+count) = 1 + '0';
    else
    *(pointer+count) = 0 + '0';
    count++;
    }
    *(pointer+count) = '\0';
    return pointer;
    }