Hexadecimal to Decimal Conversion

1#include <stdio.h>
2#include <string.h>
3#include <ctype.h>
4#include <math.h>
5
6int hexToDecimal(char hex[]) {
7    int decimal = 0;
8    int len = strlen(hex);
9    
10    for (int i = 0; i < len; i++) {
11        int digit;
12        char ch = toupper(hex[i]);
13        
14        if (ch >= '0' && ch <= '9') {
15            digit = ch - '0';
16        } else if (ch >= 'A' && ch <= 'F') {
17            digit = ch - 'A' + 10;
18        } else {
19            return -1;  // Invalid
20        }
21        
22        decimal += digit * pow(16, len - 1 - i);
23    }
24    
25    return decimal;
26}
27
28int main() {
29    char hex[] = "1A3";
30    
31    printf("Hexadecimal: %s\n", hex);
32    printf("Decimal: %d\n", hexToDecimal(hex));
33    
34    // Using scanf with format specifier
35    int num;
36    sscanf("FF", "%x", &num);
37    printf("\nHex FF = Decimal %d\n", num);
38    
39    return 0;
40}