Question

I am working on a project where I can to convert a api digit to a char. I have used an array of string pointers to get the conversion. However, I want to return just a single ch, as my api that I am using will only accept a char. So ap_five will return ‘5’. But I want to five to be a single char ‘5’.

I thought maybe I could cast to a char in the return. However, I just get rubbish.

I am sure there is other ways to solve this, how I am just wondering how can I solve with my present program.

char *digits_conversion[][2]= {     {'ap_zero', '0'},     {'ap_one', '1'},     {'ap_two', '2'},     {'ap_three', '3'},     {'ap_four', '4'},     {'ap_five', '5'},     {'ap_six', '6'},     {'ap_seven', '7'},     {'ap_eight', '8'},     {'ap_nine', '9'},     {'ap_star', '*'},     {'ap_hash', '#'},     {NULL, NULL} };  char convert_to_char(const char *digit) {     int i = 0;     for(i = 0; *digits_conversion[i][1]; i++)     {         if(strcmp(digits_conversion[i][0], digit) == 0)         {             return (char) digits_conversion[i][1];         }     }      return '\0'; }  int main(void) {     char ch;      ch = convert_to_char('ap_five');      printf('Converted digit: %c\n', ch);      return 0; } 

Answer 1

The simplest fix to your existing code is just to change:

return (char) digits_conversion[i][1]; 

into

return digits_conversion[i][1][0]; 

However, you might find that changing digits_conversion into an array of structures will give you code that is easier to understand and maintain. For example:

struct digit_mapping {     char *api_name;     char digit; }; struct digit_mapping conversion_table[] = {     { 'ap_zero', '0' },     {'ap_one', '1'},     {'ap_two', '2'},     {'ap_three', '3'},     {'ap_four', '4'},     {'ap_five', '5'},     {'ap_six', '6'},     {'ap_seven', '7'},     {'ap_eight', '8'},     {'ap_nine', '9'},     {'ap_star', '*'},     {'ap_hash', '#'},     {NULL, '\0'} };  char convert_to_char(const char *digit) {     int i = 0;     for(i = 0; conversion_table[i].digit; i++)     {             if(strcmp(conversion_table[i].api_name, digit) == 0)             {                     return conversion_table[i].digit;             }     }      return '\0'; }  int main(void) {     char ch;      ch = convert_to_char('ap_five');      printf('Converted digit: %c\n', ch);      return 0; }