1.题目要求

2.代码实现 

#include <stdio.h>
#include <ctype.h>
#include <string.h>

int hexToDec(char hex[]) {
    int len = strlen(hex);
    int base = 1;
    int dec = 0;
    for (int i = len - 1; i >= 0; i--) {
        if (isdigit(hex[i])) {
            dec += (hex[i] - '0') * base;
        } else if (isalpha(hex[i])) {
            dec += (toupper(hex[i]) - 'A' + 10) * base;
        }
        base *= 16;
    }
    return dec;
}

int main() {
    char input[80];
    printf("请输入十六进制字符串：");
    scanf("%s", input);

    char hexStr[80];
    int j = 0;
    for (int i = 0; i < strlen(input); i++) {
        if ((input[i] >= '0' && input[i] <= '9') ||
            (input[i] >= 'a' && input[i] <= 'f') ||
            (input[i] >= 'A' && input[i] <= 'F')) {
            hexStr[j++] = input[i];
        }
    }
    hexStr[j] = '\0';

    int decimal = hexToDec(hexStr);
    printf("十六进制串%s的值=十进制%.0f", hexStr, (float)decimal);

    return 0;
}

3.代码详解