For loop print twie

Question

这是我的代码

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

int main()
{
int o;

int menu;
printf("\n\t\t\t\t _________________________________________\n");
printf("\t\t\t\t|                CONVERTER                |\n");
printf("\t\t\t\t|=========================================|\n");
printf("\t\t\t\t|         |                               |\n");
printf("\t\t\t\t|    1    |    Decimal    to     Binary   |\n");
printf("\t\t\t\t|_________|_______________________________|\n");
printf("\t\t\t\t|         |                               |\n");
printf("\t\t\t\t|    2    |    Binary     to     Decimal  |\n");
printf("\t\t\t\t|_________|_______________________________|\n");
printf("\t\t\t\t|         |                               |\n");
printf("\t\t\t\t|    3    |    Octal      to     Binary   |\n");
printf("\t\t\t\t|_________|_______________________________|\n");
printf("\t\t\t\t|         |                               |\n");
printf("\t\t\t\t|    4    |    Octal      to     Decimal  |\n");
printf("\t\t\t\t|_________|_______________________________|\n");
printf("\t\t\t\t|         |                               |\n");
printf("\t\t\t\t|    5    |    Decimal    to     Octal    |\n");
printf("\t\t\t\t|_________|_______________________________|\n");
printf("\t\t\t\t|         |                               |\n");
printf("\t\t\t\t|    6    |    Hexa       to     Decimal  |\n");
printf("\t\t\t\t|_________|_______________________________|\n");
printf("\t\t\t\t|         |                               |\n");
printf("\t\t\t\t|    0    |    Quit                       |\n");
printf("\t\t\t\t|_________|_______________________________|\n");
printf("\n");

for(o=1;o<=50;o++){
printf("\n\t\t\t\t              Please select\n\n\t\t\t\t                    ");
menu = getchar();

    switch (menu)
    {
        case '1':{
            long int decimalNumber,quotient;
            int binaryNumber[100],i=1,j;
            printf("\n\t\t\t\tEnter any decimal number: ");
            scanf("%ld",&decimalNumber);
            printf("\n");

            quotient = decimalNumber;


            while(quotient!=0){

                binaryNumber[i++]= quotient % 2;

                quotient = quotient / 2;}


printf("\t\t\t\tEquivalent binary value is: ");

for(j = i -1 ;j> 0;j--){

     printf("%d",binaryNumber[j]);
}
printf("\n");
// o+= o + 1;
   }
            break;


        case '2':{
            long int binary1;
        printf("\n\t\t\t\tEnter any Binary Number:\n\n\t\t\t\t");
            scanf("%ld",&binary1);
            printf("\n\t\t\t\tEquivalent binary value is: ");
            int decimal=0;
            int i=0;
            int rem;
            while(binary1!=0)
            {
                rem = binary1%10;
                binary1/=10;
                decimal += rem*pow(2,i);
                ++i;
            }

            printf("\n\n\t\t\t\t%d\n", decimal);
        }
            break;


        case '3':{
            long int octal1;
printf("\n\t\t\t\tEnter any Octal number: ");
scanf("%ld", &octal1);
int decimal=0, binary=0, i=0;
printf("\n\t\t\t\tThe Equivalent Binary Value is: ");
while(octal1!=0)
{
    decimal+=(octal1%10)*pow(8,i);
    ++i;
    octal1/=10;
}
i=1;
while(decimal!=0)
{
    binary+=(decimal%2)*i;
    decimal/=2;
    i*=10;
}
printf("%d\n", binary);
        }
            break;


        case '4':{
                      long int octal2;
printf("\n\t\t\t\tEnter any Octal number: ");
scanf("%ld", &octal2);
int decimal2=0, i=0;
printf("\n\t\t\t\tThe Equivalent Decimal Value is: ");
while(octal2!=0)
{
    decimal2+=(octal2%10)*pow(8,i);
    ++i;
    octal2/=10;
}
        printf("%d\n", decimal2);
       }
            break;


        case '5':{
       long int decimal2,quotient2;
      printf("\n\t\t\t\tEnter any decimal number: ");

        scanf("%ld",&decimal2);
        int octal3[100],w=1,e;

        quotient2 = decimal2;
        while(quotient2!=0){


        octal3[w++]= quotient2%8;

        quotient2 = quotient2 / 8;

}
        printf("\n\t\t\t\tEquivalent octal value is: ");
        for(e=w-1;e>0;e--)
        printf("%d", octal3[e]);
        printf("\n");

        }
            break;


        case '6':{
            unsigned int q;
            printf("\n\t\t\t\tEnter any Hexadecimal number: ");
            scanf("%x", &q);
            printf("\nThe Equivalent decimal value is: ");
            printf("%d\n", q);
        }
            break;


        case '0':{

            printf("\n\t\t\t\t              Are you sure?\n\n\t\t\t\t              y or n: ");
            char b[9];
            scanf("%s", b);
            if(strcmp(b,"y")==0){
            o=o+50;
            printf("\n\n\t\t\t\t              Have a nice day!\n\n");}

            }

            break;

    }



    }


    return 0;

}

在获得菜单中某个菜单项的结果后，“请选择”短语打印2次，然后让您选择另一个菜单项。

为什么要打印2次？

这是一个转换器程序，作为我的基本编程主题的项目。我们被告知要编写一个程序来转换这些数字，在转换数字之后，程序不应该结束，应该让您选择另一个选项或选择“退出”退出程序。

Answer 1

我复制了你的代码并进行了调试。似乎在选择一个选项并输入要转换的数字后，"menu = getchar();“的值变成了10，并且不会等待用户输入开关(菜单)中没有处理的值。考虑使用scanf，因为这对我来说工作得很好。请记住，您声明的菜单是一个int而不是char，所以我猜这一定是您遇到麻烦的原因……

使用

scanf("%ld", &menu);

并像这样替换case语句。

case '1': // change to case 1:
case '2': // change to case 2:

以此类推..因为值将是int而不是char。