如何重复执行一组操作？

Question

我想制作一个程序来询问用户问题，然后用户选择一个答案，然后程序返回到原始问题目录。例如：

你最喜欢的颜色是什么？ 1. 蓝色 2. 绿色 3. 黄色

然后用户选择说“2”

那我想让它返回

你最喜欢的颜色是什么？ 1. 蓝色 2. 绿色 3. 黄色

我已经编写了代码来处理询问、选择问题的答案。我只需要帮助返回到原始问题，以便用户可以根据需要再次回答。谢谢大家！

#include <stdio.h>

int main (void)
{
   printf("\nIntroducing Space\n"); 
   printf("Brought to you in part by Free Time\n\n\n");
   while(1) {   
       int space;
       int subspace1;
       int subspace2;
       printf("What would you like to do in Space?\n");
       printf("\nDIRECTORY\n\n");
       printf("1. What is space?\n");
       printf("2. Tell me how cool I am\n");
       printf("Enter the number to your desired space\n");
       scanf("%i", &space);
       if (space == 2){
           printf("Although I have never met you, anyone in space would be considered    cool to the average eye. I mean lets be real, its space.\n\n");
           printf("Do you have any interesting hobbies or tidbits about yourself?\n\n");
           printf("1. I can play the flute blindfolded\n");
           printf("2. I can eat twelve pounds of salt water taffy in one sitting\n");
           printf("3. My uncle drives an RV\n");
           scanf("%i", &subspace2);
           if (subspace2 == 1) {
              printf("\n The flute huh? You're somethin' else\n");
           }
           if (subspace2 == 2) {
              printf("\n But let's be honest who likes salt water taffy these days anyway?\n");
           }
           if (subspace2 == 3) {
              printf("\n An RV? Now adays they call that 'homeless' but hey whatever floats your boat chief\n");
           }
      }
   }
   return 0;
}

我觉得这是我需要某种返回语句的地方，它让我回到我最初的问题“你想在太空中做什么”，以便用户可以提出另一个问题。

Answer 1

使用 do...while 而不是 while，因为您提到您至少问过一次问题。 这就是你可以做到的方式

int choice;
char ch2;
do{

printf("Option1");
printf("Option2");
printf("Option3");
scanf("%d", choice);

switch(choice){
case 1: //statements
        break;
case 2: //statements
        break;
case 3: //statements
        break;
deafult: //statements
}

printf("Do you want to continue(c) or quit(q)?");
scanf("%s", ch2)
}while(ch2 != "q");

Answer 2

循环使用if语句的方式需要注释，你写：

scanf("%i", &subspace2);
if (subspace2 == 1) {
    printf("\n The flute huh? You're somethin' else\n");
}
if (subspace2 == 2) {
    printf("\n But let's be honest who likes salt water taffy these days anyway?\n");
}
if (subspace2 == 3) {
    printf("\n An RV? Now adays they call that 'homeless' but hey whatever floats your boat chief\n");
}

前面的代码对subspace2 变量进行了三次测试。而不是使用你应该使用：

scanf("%i", &subspace2);
if (subspace2 == 1) {
    printf("\n The flute huh? You're somethin' else\n");
}
else if (subspace2 == 2) {
    printf("\n But let's be honest who likes salt water taffy these days anyway?\n");
}
else if (subspace2 == 3) {
    printf("\n An RV? Now adays they call that 'homeless' but hey whatever floats your boat chief\n");
}

仅当第一个不正确时才评估第二个分支，仅当第一个和第二个不正确时才评估第三个分支，但最好的选择可能是：

scanf("%i", &subspace2);
switch(subspace2) {
    case 1:
        printf("\n The flute huh? You're somethin' else\n");
        break;
    case 2:
        printf("\n But let's be honest who likes salt water taffy these days anyway?\n");
        break;
    case 3:
        printf("\n An RV? Now adays they call that 'homeless' but hey whatever floats your boat chief\n");
        break;
    default:
        printf("\n invalid option\n" );
}

这将通过一个跳转表来实现，它会更快。

Answer 3

您应该使用循环。您还应该查看switch 声明。 从长远来看，使用a good book for learning C 可能会更好。

例子：

#include <stdio.h>
int main() {
    char c;
    while(scanf("%c", &c) > 0) {
        switch(c) {
        case 'q':
        case 'Q':
            /* exit loop */
            break;
        default:
            /* do something */
            printf("%c", c);
        }
    }
}

Answer 4

从您的问题来看，目前尚不清楚您实际上想要实现什么，但我认为一个简单的循环就可以了。

检查此代码

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

int main (void)
{


    printf("\nIntroducing Space\n");                                
    printf("Brought to you in part by Free Time\n\n\n");


    int space;
    int subspace1;
    int subspace2;

    while (1)
    {
        printf("What would you like to do in Space?\n");                
        printf("\nDIRECTORY\n\n");
        printf("1. What is space?\n");
        printf("2. Tell me how cool I am\n");
        printf("3. no more question. I want to get out\n");


        printf("Enter the number to your desired space\n");
        scanf("%d", &space);

        if (space == 0)
            exit(0);
        else if (space ==1)
        {
            printf("First go to wikipedia and read about the space\n\n");
        }
        else if (space == 2){
            printf("Although I have never met you, anyone in space would be considered    cool to the average eye. I mean lets be real, its space.\n\n");
            printf("Do you have any interesting hobbies or tidbits about yourself?\n\n");
            printf("1. I can play the flute blindfolded\n");
            printf("2. I can eat twelve pounds of salt water taffy in one sitting\n");
            printf("3. My uncle drives an RV\n");
            scanf("%i", &subspace2);
            if (subspace2 == 1) {
                printf("\n The flute huh? You're somethin' else\n");
            }
            if (subspace2 == 2) {
                printf("\n But let's be honest who likes salt water taffy these days anyway?\n");
            }
            if (subspace2 == 3) {
                printf("\n An RV? Now adays they call that 'homeless' but hey whatever floats your boat chief\n");
            }
        }
        else
            printf("Please enter the choice properly\n\n");
    }
    return 0;
}

However, when the choice number will grow large, its better to use switch.试一试。编码愉快！

Answer 5

伪代码：

while(1) {
    //ask question 
    if (answer == 'q') //quit
       //exit from the loop, e.g.: break or return
    //....
}