您的问题代码

Question

我是一名新程序员，使用逻辑运算符时遇到了一些问题。

我制作了一个程序，该程序从用户那里获得以下数据，包括考试的主题总分不是单个科目的标记，而是添加所有这些标记并获得百分比。然后我使用逻辑运算符根据获得的百分比打印一些消息。程序正在运行，但它没有显示基于百分比的正确消息。

为什么它无法正常运行？

#include<stdio.h>
#include<stdlib.h>
int main(){

    int total_marks = 0;
    int no_of_subjects = 0;
    int subjects[no_of_subjects];
    int sum=0;
    float per=0;
    float gradeAplus=0;
    float gradeA=0;
    float gradeB=0;
    float gradeC=0;
    float gradeD=0;
    float gradeE=0;


    printf("What is the total number of subjects : ");
    scanf("%d",&no_of_subjects);
    printf("What is total number of marks in your exam : ");
    scanf("%d",&total_marks);

     gradeAplus = .9*total_marks;
     gradeA = .8*total_marks;
     gradeB = .7*total_marks;
     gradeC = .6*total_marks;
     gradeD = .5*total_marks;
     gradeE = .4*total_marks;



    for(int c=0;c<no_of_subjects;c++){
     printf("Enter the marks of your %d subject : ",c+1);
     scanf("%d",&subjects[c]);
     sum+=subjects[c];
   }

    per = ((float)sum/(float)total_marks)*100.0;

    if((per == gradeAplus)||(per > gradeAplus)){
        printf("\nCongratulation you have achieve A plus grade.You are    excellent.");
    }
    else if((per == gradeA)||((per > gradeA) && (per < gradeAplus))){
        printf("\nCongratulation you have achieve A grade.You are very good.");
    }
    else if((per==gradeB)||((per > gradeB) && (per < gradeA))){
        printf("\nWell you have achieved grade B.You are good.");
    }
    else if((per==gradeC)||((per > gradeC) && (per < gradeB))){
        printf("\nYou have achieve grade C.You have to do some hard work.");
    }
    else if((per==gradeD)||((per > gradeD) && (per < gradeC))){
        printf("\nYou have obtained grade D.You must work hard in order to pass the exam.");
    }
   else if((per==gradeE)||((per > gradeE) && (per < gradeE))){
        printf("\nYou have obtained grade E.You put a really bad performance.If you do not work hard you will be fail.");
    }
   else if(per<gradeE){
        printf("\nSorry you are fail.Try next time.\n");
    }
  else{
        printf("You have entered wrong data.");
  }


   return EXIT_SUCCESS;
}

Answer 1

您将grade计算为总标记的绝对值，但稍后将其与百分比值per进行比较。

gradeAplus = 90;
gradeA = 80;
gradeB = 70;
gradeC = 60;
gradeD = 50;
gradeE = 40;

 ...

per = sum * 100.0 / total_marks;

if (per >= gradeAplus) {
    printf("\nCongratulation you have achieve A plus grade.You are    excellent.");
}
else if (per >= gradeA) {
    printf("\nCongratulation you have achieve A grade.You are very good.");
}
else if (per >= gradeB) {
 ...

我对逻辑进行了一些优化并删掉了一些括号。注意： clean 语法是成为优秀程序员的最佳方法。

Answer 2

Hello Muslim，

您的问题代码

当您计算else if((per==gradeE)||((per > gradeE) && (per < gradeE))){ printf("\nYou have obtained grade E.You put a really bad performance.If you do not work hard you will be fail."); }时间计算出错时，您在代码中的错误和以下情况中的其他错误，

#include<stdio.h>
#include<stdlib.h>
void main(){

    int total_marks = 0;
    int no_of_subjects = 0;
    int subjects[no_of_subjects];
    int sum=0;
    float per=0.0;
    float gradeAplus=0;
    float gradeA=0;
    float gradeB=0;
    float gradeC=0;
    float gradeD=0;
    float gradeE=0;


    printf("What is the total number of subjects : ");
    scanf("%d",&no_of_subjects);
    printf("What is total number of marks in your exam : ");
    scanf("%d",&total_marks);

     gradeAplus = .9*total_marks;
     gradeA = .8*total_marks;
     gradeB = .7*total_marks;
     gradeC = .6*total_marks;
     gradeD = .5*total_marks;
     gradeE = .4*total_marks;



    for(int c=0;c<no_of_subjects;c++)
    {
         printf("Enter the marks of your %d subject : ",c+1);
         scanf("%d",&subjects[c]);
         sum+=subjects[c];
    }

    per = ((float)(sum*100.00)/(float)(total_marks*no_of_subjects));

    if(per >= gradeAplus)
    {
        printf("\nCongratulation you have achieve A plus grade.You are excellent.");
    }
    else if((per >= gradeA) && (per < gradeAplus)){
        printf("\nCongratulation you have achieve A grade.You are very good.");
    }
    else if((per >= gradeB) && (per < gradeA)){
        printf("\nWell you have achieved grade B.You are good.");
    }
    else if((per >= gradeC) && (per < gradeB)){
        printf("\nYou have achieve grade C.You have to do some hard work.");
    }
    else if((per >= gradeD) && (per < gradeC)){
        printf("\nYou have obtained grade D.You must work hard in order to pass the exam.");
    }
   else if((per >= gradeE) && (per < gradeD)){
        printf("\nYou have obtained grade E.You put a really bad performance.If you do not work hard you will be fail.");
    }
   else if(per<gradeE){
        printf("\nSorry you are fail.Try next time.\n");
    }
  else{
        printf("You have entered wrong data.");
  }

}

代码其他问题

当用户在每个主题方面输入100以上的标记（注意：如果每个科目有100个考试成绩。）时，也要给出成绩，但它无效，所以改进代码。

建议

当用户在每个主题上方输入100以上的标记时（注意：如果每个主题的试卷100分。），请给出信息（即主题标记不在100以上）并再次要求标记。< / p>

解决方案

{{1}}

Answer 3

您遇到的其他问题包括：

int no_of_subjects = 0;
int subjects[no_of_subjects];

声明subjects数组的大小为0.当您稍后更改no_of_subjects时，这不会更改数组的大小，因此您可以使用超出范围的索引。

在获得subjects

的值后，您需要移动no_of_subjects的声明

程序运行正常但逻辑运算符在C中无法正常工作

3 个答案:

您的问题代码

代码其他问题

建议

解决方案