c - If 语句问题，不显示正确的输出

Question

我正在尝试制作一个程序，让用户可以从他们想要转换的测量列表中进行选择。
到目前为止，我的代码是:

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

int main()
{
    int sv, SourceUnit, du, mb, kb, by;
    printf("--------------------------------------------------0x0 Menu:------    ---------------------------------\n");
    printf(" Please Select from the following options (enter number exactly when prompted for source units!\n");
    printf("1: Kilo -> Mega\n2: Mega -> Kilo\n10. Bits -> Bytes\n ");
    printf("--------------------------------------------------------------------------------------------------\n");

    printf("Enter source value: ");
    scanf("%d", &sv);

    printf("Enter source unit: ");
    scanf("%s", &SourceUnit);

    if (SourceUnit == 1)                                                            //convert kilobytes to megabytes
    {

        mb = (sv / 1024);
        printf("%d Kb ==  %d Mb\n", sv, mb);
    }

    else if (SourceUnit == 2)                                                           //convert megabytes to kilobytes
    {
        kb = (sv / 1024);
        printf("%d Mb == %d Kb\n", sv, kb);
    }

    else if (SourceUnit == 10)                                                          //bits to bytes
    {
        by = (sv / 8);
        printf("%d Bits == %d Bytes\n", sv, by);
    }

    else 
    {
        printf("Please Choose from the menu options to convert!\n");
    }

    return(0);
}

它在 GCC 上编译良好。我得到的输出是:

---------------------------------------0x0 Menu:----------------------------
1. Kilo -> Mega
2. Mega -> Kilo
3. Bits -> Bytes
----------------------------------------------------------------------------
Enter Source Value: (Example I will type in 30 for the number to be converted) 30
Enter Source Unit: (Example will be 1 to convert from Kilo to Mega) 1
Please Choose from the menu options to convert! 

出于某种原因，当我不希望它出现时，我的 else 语句出现了......是什么导致了这个错误？

此外，我还遇到了一些问题，我需要将 deka 转换为 dibi..具体如何完成？我知道 deka 是 10 人一组，dibi 是 16 人一组，但这就是我能读到的关于它们的所有信息..

Answer 1

您的 scanf 有错误的格式说明符。它应该是“%d”。这导致了问题。

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

int main()
{
    int sv, SourceUnit, du, mb, kb, by;
    printf("--------------------------------------------------0x0 Menu:------    ---------------------------------\n");
    printf(" Please Select from the following options (enter number exactly when prompted for source units!\n");
    printf("1: Kilo -> Mega\n2: Mega -> Kilo\n10. Bits -> Bytes\n ");
    printf("--------------------------------------------------------------------------------------------------\n");

    printf("Enter source value: ");
    scanf("%d", &sv);

    printf("Enter source unit: ");
    scanf("%d", &SourceUnit); //This should be %d

    if (SourceUnit == 1)                                                            //convert kilobytes to megabytes
    {

        mb = (sv / 1024);
        printf("%d Kb ==  %d Mb\n", sv, mb);
    }

    else if (SourceUnit == 2)                                                           //convert megabytes to kilobytes
    {
        kb = (sv / 1024);
        printf("%d Mb == %d Kb\n", sv, kb);
    }

    else if (SourceUnit == 10)                                                          //bits to bytes
    {
        by = (sv / 8);
        printf("%d Bits == %d Bytes\n", sv, by);
    }

    else
    {
        printf("Please Choose from the menu options to convert!\n");
    }

    return(0);
}