在c中将十六进制数转换为十进制数

Question

我正在实现一个程序，将十六进制数转换为十进制数，但我的程序无法正常工作。请帮助我使程序正常运行。

不知道程序的哪一部分有bug。任何建议和答案都会有帮助。

代码:

#include <stdio.h>
#include <math.h>

char hexNum[100];
int getDecimal();

int main(int argc, char **argv) {
    printf("Enter the hex number: ");
    int i = 0;
    char ch;
    while ((ch = getchar()) != '\n') {
        hexNum[i++] = ch;
    }
    hexNum[i] = '\0';
    printf("\nHexadecimal Number is: %s", hexNum);
    int n = getDecimal();
    printf("\nDecimal Number is: " + n);
    return 0;
}

int getDecimal() {
    //get to the units digit index
    int index = 0;
    while (hexNum[index + 1] != '\0') {
        index++;
    }
    //calculate the decimal value and store the result in result var
    int var = 0;  //store the decimal number
    int exp = 0;  //keep track of exponent of 16^x
    while (index >= 0) {
        int ch = hexNum[index--];
        switch (ch) {
        case 'a':
            var = var + (10 * pow(16, exp++));
            break;
        case 'b':
            var = var + (11 * pow(16, exp++));
            break;
        case 'c':
            var = var + (12 * pow(16, exp++));
            break;
        case 'd':
            var = var + (13 * pow(16, exp++));
            break;
        case 'e':
            var = var + (14 * pow(16, exp++));
            break;
        case 'f':
            var = var + (15 * pow(16, exp++));
            break;
        default:   //if its a digit
            var = var + ((ch-'0') * pow(16, exp++));
            break;
        }
    }
    return var;
}

Answer 1

更改此行:

    printf("\nDecimal Number is: " + n);

至

    printf("\nDecimal Number is: %d\n", n);

而且你的算法太复杂，性能很差。

最好使用前向迭代而不是后向迭代。像这样的东西:

var = 0;
index = 0;
while (hexNum[index]  != '\0')
{
    var = 16 * var;

    switch (hexNum[index]) {
    case 'a':
        var = var + 10;
        break;
    case 'b':
        var = var + 11;
        break;
    ... and so on ...
    }
    ++index;
}
return var;