实验7 文件应用编程

实验四：

#include<stdio.h>
#define N 100
int main(){
    int m=0,i,num=0 ;
    char a[N] ;
    FILE *fp ;
    fp=fopen("data4.txt","r") ;
    if(!fp){
        printf("failed to open...") ;
        return ;
    }
    while(fgets(a,N,fp)!=NULL)
        num+=1 ;
    
    for(i=0;i<strlen(a);i++){
       if(a[i]=='\n' && a[i]=='\t')
          m+=1 ;
        }

    fclose(fp) ;
    
    printf("行数：%-20d\n",m) ;
    printf("字符数（不计空白符）：%-20d\n",num) ;
    return 0 ;
} 

 实验五：

#include <stdio.h>
#include <string.h>

#define N 10

typedef struct {
    long id;            // 准考证号
    char name[20];      // 姓名
    float objective;    // 客观题得分
    float subjective;   // 操作题得分
    float sum;          // 总分
    char result[10];    // 考试结果
} STU;

// 函数声明
void read(STU st[], int n);
void write(STU st[], int n);
void output(STU st[], int n);
int process(STU st[], int n, STU st_pass[]);

int main() {
    STU stu[N], stu_pass[N];
    int cnt;
    double pass_rate;

    printf("从文件读入%d个考生信息...\n", N);
    read(stu, N);

    printf("\n对考生成绩进行统计...\n");
    cnt = process(stu, N, stu_pass);

    printf("\n通过考试的名单:\n");
    output(stu, N);   // 输出所有考生完整信息到屏幕
    write(stu, N);    // 输出考试通过的考生信息到文件

    pass_rate = 1.0 * cnt / N;
    printf("\n本次等级考试通过率: %.2f%%\n", pass_rate*100);

    return 0;
}

// 把所有考生完整信息输出到屏幕上
// 准考证号，姓名，客观题得分，操作题得分，总分，结果
void output(STU st[], int n) {
    int i;
    
    printf("准考证号\t姓名\t客观题得分\t操作题得分\t总分\t\t结果\n");
    for (i = 0; i < n; i++)
        printf("%ld\t\t%s\t%.2f\t\t%.2f\t\t%.2f\t\t%s\n", st[i].id, st[i].name, st[i].objective, st[i].subjective, st[i].sum, st[i].result);
}

// 从文本文件examinee.txt读入考生信息:准考证号，姓名，客观题得分，操作题得分
void read(STU st[], int n) {
    int i;
    FILE *fin;

    fin = fopen("examinee.txt", "r");
    if (!fin) {
        printf("fail to open file\n");
        return;
    }

    while (!feof(fin)) {
        for (i = 0; i < n; i++)
            fscanf(fin, "%ld %s %f %f", &st[i].id, st[i].name, &st[i].objective, &st[i].subjective);
    }

    fclose(fin);
}

void write(STU s[], int n) {
    FILE *fp ;
    fp = fopen("data4.txt", "w") ;
    if (fp == NULL) {
        printf("failed to open...") ;
        return ;
    }
    int i;
    for ( i = 0; i < n; i++) {
        if (s[i].sum >= 60) {
            fprintf(fp, "%ld %s %.2f %.2f %.2f %s\n", s[i].id, s[i].name, s[i].objective, s[i].subjective, s[i].sum, s[i].result);
        }
    }
    fclose(fp) ;

}

int process(STU st[], int n, STU st_pass[]) {
    int num = 0 ,i ;
    for ( i = 0; i < n; i++) {
        st[i].sum = st[i].objective + st[i].subjective ;
        if (st[i].sum >= 60) {
            strcpy(st[i].result, "通过") ;
            st_pass[num] = st[i] ;
            num+=1 ;
        } else {
            strcpy(st[i].result, "不通过") ;
        }
    }
    return num ;
}
    

 

 实验六：

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#define STU_num 100

typedef struct{
    int num ;
    char name[10] ;
    char class[20] ;
}STU;

void read(STU students[]) {
    int i ;
    FILE *fp ;
    fp = fopen("list.txt", "r") ;
    if (fp == NULL) {
        printf("failed to open...") ;
        return ;
    }
    for (i = 0; i < STU_num; i++) {
        fscanf(fp, "%d %s %s", &students[i].num, &students[i].name, &students[i].class);
    }
    fclose(fp) ;
}

void random(STU students[], STU selected[], int num) {
    int i,selected_index[STU_num] = {0} ;
    srand((unsigned int)time(NULL)) ;
    for(i = 0; i < STU_num; i++) {
        int index;
        do {
            index = rand() % STU_num ;
        } while (selected_index[index] == 1) ;
        selected_index[index] = 1 ;
        selected[i] = students[index] ;
    }
}

void output(STU selected[], int num) {
    int i ; 
    printf("------随机抽点名单------\n");
    for (i = 0; i < STU_num; i++) {
        printf("%d %s %s\n", selected[i].num, selected[i].name, selected[i].class);
    }
}


void write(STU selected[], int n, char *filename) {
    FILE *fp;
    fp = fopen("dian ming.txt", "w") ;
    if (fp == NULL) {
        printf("failed to open...") ;
        return ;
    }
    for (int i = 0; i < STU_num; i++) {
        fprintf(fp, "%d %s %s\n", selected[i].num, selected[i].name, selected[i].class);
    }
    fclose(fp) ;
}


int main(){
    STU students[STU_num];
    STU selected[5];
    char filename[20];

    read(students);

    random(students, selected, 5);

    display(selected, 5);

    write(selected, 5, filename);

    return 0 ;
}