Question

我正在编写一个程序，当给出表达式时，忽略PEMDAS规则，并且只是吐出严格的从左到右的答案（例如5 + 4 * 4/6 = 6）。我已接近完成它，但我再也无法获得输出了。我从一次获得输出后就做出了改变。但现在它不会给我任何东西。看看我之前和之后的镜头！第一部分代码工作，只有在你按Enter键并给它一个随机的int值...它需要另一个int值来完成我设置的while循环。第二个不起作用。我所做的改变是我设置了一个值ck，这会检查汽车是否有值，即= 1.如果没有，则循环结束。让我知道你的想法。非常感谢你的帮助。

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

int main(void){
  int num, total;
  char car;
  //Setting up integers and a char value

  printf("Please enter an expression to be evaluated: \n");
  scanf("%d", &total); // User prompt, grabs the first value. Stores in total.

   while(car != '\n'){

   scanf(" %c", &car);
   scanf("%d", &num);

    if(car == '*'){
    total = (total*num);
    } // Multiplies total and new number value if '*' is enterd

   else if(car == '/'){
     total = (total/num);
   } // Divides total and new number value if '/' is entered

   else if(car == '+'){
     total = (total+num);
   } // Adds total and new number value if '+' is entered

   else if(car == '-'){
     total = (total-num);
   } // Subtracts total and new number value if '-' is entered

       else if(car == '\n'){
       printf("%d\n", total):
   }    
 }
}

=============================================== ===========================================

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

int main(void){
  int num, total;
  char car;
  int ck = 1; //Setting up integers and a char value

  printf("Please enter an expression to be evaluated: \n");
  scanf("%d", &total); // User prompt, grabs the first value. Stores in total.

   while(ck == 1 ){

   scanf(" %c", &car);
   scanf("%d", &num);

   ck = scanf(" %c", &car);
   if(ck != 1){
     printf("%d\n", total);
   }//Newest code input

    if(car == '*'){
    total = (total*num);
    } // Multiplies total and new number value if '*' is enterd

   else if(car == '/'){
     total = (total/num);
   } // Divides total and new number value if '/' is entered

   else if(car == '+'){
     total = (total+num);
   } // Adds total and new number value if '+' is entered

   else if(car == '-'){
     total = (total-num);
   } // Subtracts total and new number value if '-' is entered

    //   else if(car == '\n'){
    //   printf("%d\n", total):
    //   }
    // Old end to if statement block, gives output. But only after another int
    // is put in.
 }
}

Answer 1

只需将scanf("%c", &car);带到while，然后在while结束前再次放置，即可修改您的第一个代码。将printf移出while。这是您修改后的代码

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

int main(void){
    int num, total;
    char car;

    printf("Please enter an expression to be evaluated: \n");
    scanf("%d", &total); // User prompt, grabs the first value. Stores in total.
    scanf("%c", &car);
    while(car != '\n'){
        scanf("%d", &num); //Newest code input

        if(car == '*'){
            total = (total*num);
        } // Multiplies total and new number value if '*' is enterd

        else if(car == '/'){
              total = (total/num);
        } // Divides total and new number value if '/' is entered

        else if(car == '+'){
             total = (total+num);
        } // Adds total and new number value if '+' is entered

        else if(car == '-'){
             total = (total-num);
        }
        scanf("%c", &car);
    } 
    printf ("%d", total);
    return 0;
}

Answer 2

这里的问题是您同时要求操作员（汽车）和号码（ num ）。您应首先询问 car ，然后检查它是否不是'\ n'，然后询问该号码。以下是对您的第二个版本的修改：

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

int main(void) {
    int num, total;
    char car;
    int ck = 1; //Setting up integers and a char value
    printf("Please enter an expression to be evaluated: \n");
    scanf("%d", &total); // User prompt, grabs the first value. Stores in total.
    while(ck == 1 ) {
        scanf("%c", &car);
        if (car !='\n') {
            scanf("%d", &num);

            if(car == '*') {
                total = (total*num);
            } // Multiplies total and new number value if '*' is enterd

            else if(car == '/') {
                total = (total/num);
            } // Divides total and new number value if '/' is entered

            else if(car == '+') {
                total = (total+num);
            } // Adds total and new number value if '+' is entered

            else if(car == '-') {
                total = (total-num);
            } // Subtracts total and new number value if '-' is entered
        } else {
            ck=0; //break the while loop
        }
    }
    printf("%d\n", total);
}

我的“Disregard PEMDAS”数字计算器没有结果

2 个答案: