C語言實現十六進制字符串轉數字

代碼：

int StringToInt(char *hex)
{
    return CharToInt(hex[0]) * 16 + CharToInt(hex[1]);
}


int CharToInt(char hex) 
{
    if (hex>='0' && hex <='9')
        return hex - '0';
    if (hex>='A' && hex <= 'F')
        return hex-'A'+10;
    if(hex>='a' && hex <= 'f')
        return hex-'a'+10;
    return -1;
}