C //习题 7.14 输入10个学生5门课的成绩，分别用函数实现下列功能：1.计算每个学生的平均分；2.计算每门课的平均分；3.找出所有50个分数中最高的分数所对应的学生和课程；4.计算平均分方差。

时间：2024-10-27 11:32:28

C程序设计 （第四版） 谭浩强 习题7.14

习题 7.14 输入10个学生5门课的成绩，分别用函数实现下列功能：

1. 计算每个学生的平均分；
2. 计算每门课的平均分；
3. 找出所有50个分数中最高的分数所对应的学生和课程；
4. 计算平均分方差：

σ = 1 n ∑ x i 2 − ( ∑ x i n ) 2 \sigma=\frac{1}{n}\sum x_i^2-\Bigg(\frac{\sum x_i}{n}\Bigg)^2 σ=n1​∑xi2​−(n∑xi​​)2

其中， x i x_i xi​为某一学生的平均分。
IDE工具：VS2010
Note: 使用不同的IDE工具可能有部分差异。

 

代码块
方法1：使用数组
#include <>
#include <>

void inputScore(float stuScore[][5], int stu, int course){
	printf("Enter the scores of %d students in %d courses:\n", stu, course);
	for(int i = 0; i < stu; i++){
		printf("Enter No.%d student scores in %d courses:\n", i+1, course);
		for(int j = 0; j < course; j++){
			printf("Enter No.%d course score: ", j+1);
			scanf("%f", &stuScore[i][j]);
			while(stuScore[i][j] < 0 || stuScore[i][j] > 100){
				printf("Score Error! Retry!\nEnter No.%d course score: ", j+1);
				scanf("%f", &stuScore[i][j]);
			}
		}
	}
	printf("\n");
}

void stuScoreAverage(float stuScore[][5], int stu, int course, float *stuAver){
	float sum = 0.0;
	int k = 0;
	for(int i = 0; i < stu; i++){
		for(int j = 0; j < course; j++){
			sum += stuScore[i][j];
		}
		stuAver[k++] = sum / course;
		printf("The average score of No.%d student is %.2f\n", i+1, sum/course);
		sum = 0.0;
	}
	printf("\n");
}

void courseAverage(float stuScore[][5], int stu, int course){
	float sum = 0.0;
	for(int i = 0; i < course; i++){
		for(int j = 0; j < stu; j++){
			sum += stuScore[j][i];
		}
		printf("The average score of No.%d course is %.2f\n", i+1, sum/stu);
		sum = 0.0;
	}
	printf("\n");
}

void highestScore(float stuScore[][5], int stu, int course){
	float highScore = stuScore[0][0];
	int highStu, highCourse;
	for(int i = 0; i < stu; i++){
		for(int j = 0; j < course; j++){
			if(stuScore[i][j] > highScore){
				highScore = stuScore[i][j];
				highStu = i + 1;
				highCourse= j + 1;
			}
		}
	}
	printf("The highest score is %.2f, No.%d Student, No.%d Course\n\n", highScore, highStu, highCourse);
}

void meanVariance(float stuScore[][5], int stu, int course, float *stuAver){
	float sum1 = 0.0;
	float sum2 = 0.0;
	for(int i = 0; i < stu; i++){
		sum1 += stuAver[i] * stuAver[i];
		sum2 += stuAver[i];
	}
	float sigma = sum1 / stu - (sum2 / stu) * (sum2 / stu);
	printf("The mean variance is %.2f\n", sigma);
}

int main(){
	float stuScore[10][5];
	float stuAver[10];
	
	inputScore(stuScore, 10, 5);
	stuScoreAverage(stuScore, 10, 5, stuAver);
	courseAverage(stuScore, 10, 5);
	highestScore(stuScore, 10, 5);
	meanVariance(stuScore, 10, 5, stuAver);
	
	system("pause");
    return 0;
}
方法2：使用指针、函数指针、动态分配内存
#include <>
#include <>

#define S 10    //定义学生数
#define C 5    //定义课程数

//初始化参数
void initialStuScore(float ***stuScore, int stu, int course, float **stuAver){
	*stuScore = (float**)malloc(stu * sizeof(float*));
	for(int i = 0; i < stu; i++){
		(*stuScore)[i] = (float*)malloc(course * sizeof(float));
	}
	*stuAver = (float*)malloc(stu * sizeof(float));
}

//输入课程成绩
void inputScore(float **stuScore, int stu, int course){
	printf("Enter the scores of %d students in %d courses:\n", stu, course);
	for(int i = 0; i < stu; i++){
		printf("Enter No.%d student scores in %d courses:\n", i+1, course);
		for(int j = 0; j < course; j++){
			printf("Enter No.%d course score: ", j+1);
			scanf("%f", &stuScore[i][j]);
			//成绩不合理报错，重新输入
			while(stuScore[i][j] < 0 || stuScore[i][j] > 100){
				printf("Score Error! Retry!\nEnter No.%d course score: ", j+1);
				scanf("%f", &stuScore[i][j]);
			}
		}
	}
	printf("\n");
}

void stuScoreAverage(float **stuScore, int stu, int course, float *stuAver){
	float sum = 0.0;
	int k = 0;
	for(int i = 0; i < stu; i++){
		for(int j = 0; j < course; j++){
			sum += stuScore[i][j];
		}
		stuAver[k++] = sum / course;
		printf("The average score of No.%d student is %.2f\n", i+1, sum/course);
		sum = 0.0;
	}
	printf("\n");
}

void courseAverage(float **stuScore, int stu, int course, float *stuAver){
	float sum = 0.0;
	for(int i = 0; i < course; i++){
		for(int j = 0; j < stu; j++){
			sum += stuScore[j][i];
		}
		printf("The average score of No.%d course is %.2f\n", i+1, sum/stu);
		sum = 0.0;
	}
	printf("\n");
}

void highestScore(float **stuScore, int stu, int course, float *stuAver){
	float highScore = stuScore[0][0];
	int highStu, highCourse;
	for(int i = 0; i < stu; i++){
		for(int j = 0; j < course; j++){
			if(stuScore[i][j] > highScore){
				highScore = stuScore[i][j];
				highStu = i + 1;
				highCourse= j + 1;
			}
		}
	}
	printf("The highest score is %.2f, No.%d Student, No.%d Course\n\n", highScore, highStu, highCourse);
}

void meanVariance(float **stuScore, int stu, int course, float *stuAver){
	float sum1 = 0.0;
	float sum2 = 0.0;
	for(int i = 0; i < stu; i++){
		sum1 += stuAver[i] * stuAver[i];
		sum2 += stuAver[i];
	}
	float sigma = sum1 / stu - (sum2 / stu) * (sum2 / stu);
	printf("The mean variance is %.2f\n", sigma);
}

//调用函数的函数
void function(float **stuScore, int stu, int course, float *stuAver, void (*fun[])(float**, int, int, float*)){
	for(int i = 0; i < 4; i++){
		fun[i](stuScore, stu, course, stuAver);
	}
}

//释放内存
void freeStuScore(float ***stuScore, int stu, int course, float **stuAver){
	for(int i = 0; i < stu; i++){
		free((*stuScore)[i]);
	}
	free(*stuScore);
	free(*stuAver);
}

int main(){
	float **stuScore = NULL;
	float *stuAver = NULL;
	void (*fun[4])(float**, int, int, float*) = {stuScoreAverage, courseAverage, highestScore, meanVariance};

	initialStuScore(&stuScore, S, C, &stuAver);
	inputScore(stuScore, S, C);
	function(stuScore, S, C, stuAver, fun);
	freeStuScore(&stuScore, S, C, &stuAver);

	system("pause");
    return 0;
}
方法3：使用结构体
#include <>
#include <>

#define S 10
#define C 5

struct Student{
	float score[C];
	void inputScore(int s, int c);
	float courseAverage(int c);
	float highestScore(int c);
	int courseHighScore;
};

void Student::inputScore(int s, int c){
	printf("Enter No.%d student scores in %d courses:\n", s, c);
	for(int i = 0; i < c; i++){
		printf("Enter No.%d course score: ", i+1);
		scanf("%f", &score[i]);
		while(score[i] < 0 || score[i] > 100){
			printf("Score Error! Retry!\nEnter No.%d course score: ", i+1);
			scanf("%f", &score[i]);
		}
	}
	printf("\n");
}

float Student::courseAverage(int c){
	float sum = 0.0;
	for(int i = 0; i < c; i++){
		sum += score[i];
	}
	return sum / c;
}

float Student::highestScore(int c){
	float high = 0;
	for(int i = 0; i < c; i++){
		if(score[i] > high){
			high = score[i];
			courseHighScore = i + 1;
		}
	}
	return high;
}

void initialStu(Student **stu, int s){
	*stu = (Student*)malloc(s * sizeof(Student));
}

void inputStu(Student *stu, int s, int c){
	printf("Enter the scores of %d students in %d courses:\n", s, c);
	for(int i = 0; i < s; i++){
		stu[i].inputScore(i+1, c);
	}
}

void stuScoreAverage(Student *stu, int s, int c){
	for(int i = 0; i < s; i++){
		printf("The average score of No.%d student is %.2f\n", i+1, stu[i].courseAverage(c));
	}
}

void stuCourseAverage(Student *stu, int s, int c){
	float sum = 0.0;
	for(int i = 0; i < c; i++){
		for(int j = 0; j < s; j++){
			sum += stu[j].score[i];
		}
		printf("The average score of No.%d course is %.2f\n", i+1, sum/s);
	}
	printf("\n");
}

void highestScore(Student *stu, int s, int c){
	float high = stu[0].highestScore(c);
	int n;
	for(int i = 0; i < s; i++){
		if(stu[i].highestScore(c) > high){
			high = stu[i].highestScore(c);
			n = i;
		}
	}
	printf("The highest score is %.2f, No.%d student, No.%d Course\n\n", high, n+1, stu[n].courseHighScore);
}

void meanVariance(Student *stu, int s, int c){
	float sum1 = 0.0;
	float sum2 = 0.0;
	for(int i = 0; i < s; i++){
		sum1 += stu[i].courseAverage(c) * stu[i].courseAverage(c);
		sum2 += stu[i].courseAverage(c);
	}
	float sigma = sum1 / s - (sum2 / s) * (sum2 / s);
	printf("The mean variance is %.2f\n", sigma);
}

void function(Student *stu, int s, int c, void (*fun[])(Student*, int, int)){
	for(int i = 0; i < 5; i++){
		fun[i](stu, s, c);
	}
}

void freeStu(Student **stu){
	free(*stu);
}

int main(){
	Student *stu = NULL;	
	void (*fun[5])(Student*, int, int) = {inputStu, stuScoreAverage, stuCourseAverage, highestScore, meanVariance};

	initialStu(&stu, S);
	function(stu, S, C, fun);
	freeStu(&stu);

	system("pause");
	return 0;
}
解答评论1
#include <>
#include <>

float average1(float a[][5], int n);
float average2(float a[][5], int b);

int main(){
	int i,j;
	float a[10][5];
	
	for(i = 0; i < 10; i++)
		for(j = 0; j < 5; j++)
			scanf("%f",&a[i][j]);
	for(i = 0; i < 10; i++)
		printf("第%d名同学平均分为%f\n",i, average1(a, i));
	for(j = 0; j < 5; j++)
		printf("第%d门课程平均分为%f\n",j,average2(a, j));
		
	system("pause");
	return 0;
}

float average1(float a[][5],int n){
	int c;
	float d;
	float sum = 0;
	for(c = 0; c < 5; c++)
		sum = sum + a[n][c];
	d = sum / 5;
	return d;
}

float average2(float a[][5],int b){
	int c;
	float k;
	float sum = 0;
	for(c = 0; c < 10; c++)
		sum = sum + a[c][b];
	k = sum / 10;
	return k;
}

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