while循環內的if語句無法執行並退出程序

Question

所以我的主要問題是這段代碼的后半部分，尤其是：

      printf("Do you want to evaluate another teacher? (y/n) : ");
      printf("\n");
      scanf(" %c", &loop);
      if(loop != 'y' && loop != 3)
        loop='n';

我正在創建一個進行調查的程序。 但是，該學生最多只能進行3個調查，並且在每次調查結束時都會詢問他們是否要進行其他調查。 他們進行了第三次調查后，我的問題發生了。 之后，調查將提示Do you want to evaluate another teacher? (y/n)的相同問題Do you want to evaluate another teacher? (y/n) Do you want to evaluate another teacher? (y/n) ，如果學生回答y則代碼將循環返回並讓他們進行另一項調查，而不是聽我的條件，該條件在進行三項調查后便會自動結束。 如果他們回答n它仍然會重新進入循環！

對於如何使我的代碼的這一部分與我的其余代碼一起並存和工作，我感到非常困惑。 幫助將不勝感激！

如果您願意，這是我的全部代碼：

#include <stdio.h>

int main()
{
  int i = 0;
  char loop='y';


  while(loop == 'y' ){
    for(i = 0; i<4; i++){

      int num1,num2,num3,num4,num5,num6,num7,num8;
      int result;
      int input;
      char name[30];
      char teacher[30];

     printf("Enter your name : ");
      scanf("%s", &name);
      printf("\n");
      printf("Which teacher do you want to evaluate : ");
      scanf( "%s/n", &teacher);
      printf("\n");
      printf("Answer with 1 for Never upto 7 for Frequently\n");
      printf("\n");
      printf("How often does the teacher indicate where the class is going? \n ");
      scanf("%d",&num1);
      printf("How often does the teacher explain material clearly? \n ");
      scanf("%d",&num2);
      printf("How often is the teacher available outside of class? \n ");
      scanf("%d",&num3);
      printf("How often does the teacher provide helpful comments on papers and exams? \n ");
      scanf("%d",&num4);
      printf("How often does the teacher stimulate interest in material? \n ");
      scanf("%d",&num5);
      printf("How often does the teacher adjust the pace of class to the students' level of understanding? \n ");
      scanf("%d",&num6);
      printf("How often does the teacher effectively encourage students to ask questions and give answers? \n ");
      scanf("%d",&num7);
      printf("How is the teacher tolerant of different opinions expressed in class? \n ");
      scanf("%d",&num8);

      printf("******************************************************************************\n");
      printf("******************************************************************************\n");
      printf("Student's name : %s.\n", name);
      printf("Teacher's name : %s.\n", teacher);
      printf("How often does the teacher indicate where the class is going: %d\n",num1);
      printf("How often does the teacher explain material clearly : %d\n",num2);
      printf("How often is the teacher available outside of class : %d\n",num3);
      printf("How often does the teacher provide helpful comments on papers and exams: %d\n",num4);
      printf("How often does the teacher stimulate interest in material: %d\n",num5);
      printf("How often does the teacher adjust the pace of class to the students' level of understanding: %d\n",num6);
      printf("How often does the teacher effectively encourage students to ask questions and give answers: %d\n",num7);
      printf("How is the teacher tolerant of different opinions expressed in class: %d\n",num8);
      printf("******************************************************************************\n");
      printf("******************************************************************************\n");

      printf("Do you want to evaluate another teacher? (y/n) : ");
      printf("\n");
      scanf(" %c", &loop);
      if(loop != 'y' && loop != 3)
        loop='n';
    }
    return 0;
  }
}

Answer 1

您確實需要while 和 for循環嗎？ for循環在做什么？

在您的代碼中，您有兩個循環，並且稍加小心，您應該能夠將其簡化為其中一個循環。 特別是，您的return似乎在while循環內，這意味着它非常混亂。 弄清楚循環應該做什么，然后再去做。

Answer 2

if語句

if(loop != 'y' && loop != 3)
        loop='n';

應該在for循環之外。 無論如何，您都不需要兩個循環。 您應該將其更改為僅使用一個循環。 並且此if語句應該是該循環結束之前的最后一條語句。

Answer 3

您無緣無故地使用了2個循環，而且每次都要求輸入用戶名。

這是您應該如何做：

#include <stdio.h>


int main()
{
  int i = 0;
  char loop;


  int count=0;  //new variable to know how many times he filled the survey

  //You dont need to ask about your name everytime...
  char name[30];
  printf("Enter your name : ");
  scanf("%s", &name);
  printf("\n");


  do{


      int num1,num2,num3,num4,num5,num6,num7,num8;
      int result;
      int input;
      char teacher[30];


      printf("Which teacher do you want to evaluate : ");
      scanf( "%s/n", &teacher);
      printf("\n");
      printf("Answer with 1 for Never upto 7 for Frequently\n");
      printf("\n");
      printf("How often does the teacher indicate where the class is going? \n ");
      scanf("%d",&num1);
      printf("How often does the teacher explain material clearly? \n ");
      scanf("%d",&num2);
      printf("How often is the teacher available outside of class? \n ");
      scanf("%d",&num3);
      printf("How often does the teacher provide helpful comments on papers and exams? \n ");
      scanf("%d",&num4);
      printf("How often does the teacher stimulate interest in material? \n ");
      scanf("%d",&num5);
      printf("How often does the teacher adjust the pace of class to the students' level of understanding? \n ");
      scanf("%d",&num6);
      printf("How often does the teacher effectively encourage students to ask questions and give answers? \n ");
      scanf("%d",&num7);
      printf("How is the teacher tolerant of different opinions expressed in class? \n ");
      scanf("%d",&num8);

      printf("******************************************************************************\n");
      printf("******************************************************************************\n");
      printf("Student's name : %s.\n", name);
      printf("Teacher's name : %s.\n", teacher);
      printf("How often does the teacher indicate where the class is going: %d\n",num1);
      printf("How often does the teacher explain material clearly : %d\n",num2);
      printf("How often is the teacher available outside of class : %d\n",num3);
      printf("How often does the teacher provide helpful comments on papers and exams: %d\n",num4);
      printf("How often does the teacher stimulate interest in material: %d\n",num5);
      printf("How often does the teacher adjust the pace of class to the students' level of understanding: %d\n",num6);
      printf("How often does the teacher effectively encourage students to ask questions and give answers: %d\n",num7);
      printf("How is the teacher tolerant of different opinions expressed in class: %d\n",num8);
      printf("******************************************************************************\n");
      printf("******************************************************************************\n");

     count++; 

     if (count<3) {
      printf("Do you want to evaluate another teacher? (y/n) : ");
      printf("\n");
      scanf("%s", &loop);
     }



  } while (loop=='y' && count<3);

  return 0;
}

Answer 4

這是更正的版本。 我只關注您的問題，而不關注您的代碼可能存在的任何其他問題。

int main() {
  int i;
  char loop;

  for(i = 0; i < 3; i++) {
    if(i != 0) { //After the first survey, prompt before we interview them
      printf("Do you want to evaluate another teacher? (y/n) : \n");
      scanf(" %c", &loop);
      if(loop != 'y')
        break; //Quit the loop
    }
    //*** Survey prompts here ***
  }
}