how to convert a concatenate string of characters to decimal numbers

Question

Basically the code below result in in a concatenate string of characters that is placed in "dec". The memory reading from the function which goes through the line of code below is 101E34 which is "dec" should be converted to 163052. How do I convert that string?

   for (int j = 0; j <2; j++)
       {
           char temp[100]= "";
           sprintf(temp, "%x", readArray[j]);
           if (strlen(temp) < 4)
              {
                  char dec[100] = "";
                  for (int r = 0; r < 4 - strlen(temp); r++)
                      {
                          strcat(dec,"0");
                      }
                          strcat(dec, temp);
               }
         }

Answer 1

#include <stdio.h>

int main() {
  char input[] = "101E34";
  char output[100];
  int i = 0, j = 0, k = 0;
  for(i = 0; i < 6;) {
    if(input[i] >= '0' && input[i] <= '9')
      j = (input[i] - '0')<< 4;
    else if(input[i] >= 'A' && input[i] <= 'Z')
      j = (input[i] - 'A' + 10)<< 4;
    else if(input[i] >= 'a' && input[i] <= 'z')
      j = (input[i] - 'a' + 10)<< 4;


    if(input[i + 1] >= '0' && input[i + 1] <= '9')
      j = j + (input[i + 1] - '0');
    else if(input[i + 1] >= 'A' && input[i + 1] <= 'Z')
      j = j + (input[i + 1] - 'A' + 10);
    else if(input[i + 1] >= 'a' && input[i + 1] <= 'z')
      j = j + (input[i + 1] - 'a' + 10);

    k += snprintf((output + k), (100 - k), "%d", j);
    i = i + 2;
  }
  puts(output);
  return 0;
}

The only restriction is on the size of output . You may need to dynamically allocate it if the input is big or changes in every run.