C、字符串、文件

Question

名为“grades.txt”的文件包含类(class)的学生成绩，格式如下，以空格分隔:(示例文件如下)

First name Last name Midterm Final
Ali Caliskan 60 40
Veli Dalgaci 80 10
Turkan Sevimli 90 50
Ali Yilmaz 30 70
Ahmet Koc 50 50

编写一个程序，计算学生的总体成绩并将其写入两个单独的文件:“passed.txt”和“failed.txt”。期中考试占成绩的40%，期末考试占成绩的60%。通过分数为 50。示例输出文件如下:

First name Last name Midterm Final Overall
passed.txt:
Turkan Sevimli 90 50 66
Ali Yilmaz 30 70 54
Ahmet Koc 50 50 50
failed.txt: 
Ali Caliskan 60 40 48
Veli Dalgaci 80 10 38

我可以读取“grades.txt”，但无法存储它们。这是我的代码；

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

int main(void) {
char* string[100];
char line[100];
char junk[100];

FILE *file = fopen("grades.txt", "r");
if(!file) {
    printf("Could not open file. Exiting application. Bye");
    return 1;
}
while(!feof(file)) {
    fscanf(file,"%[^ \n\t\r]s",line); //Get text
    printf("%s\n", line);
    fscanf(file,"%[ \n\t\r]s",junk); //Remove any 'white space' characters
    }
fclose(file);
}

<小时/>

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

int main() {

    FILE *pToFile = fopen("grades.txt","r");

    int line = 0;
    char * pch;
    char input[512];

    while( fgets( input, 512, pToFile ))
        {
        line++;
        printf("%s",input);
        }

    printf("\n\nEnd Of Program\n");

    fclose(pToFile);

    return 0;

}

我也写了它，但是这个没有分隔txt行，我认为继续这个代码会更难。

Answer 1

我建议您对 Student 使用 struct。

typedef struct {
    char first[25], last[25];
    int midterm, final;
} Student;

然后从文件中读取并填充您的结构。您可以使用这样的函数从一行构建您的struct。

  int scan_student(Student *e, const char *line);

并使用函数写入文件。

void write_student(FILE *fp, const char *tag, const Student *e, double score);

完整程序如下。

#include <stdio.h>

typedef struct {
    char first[25], last[25];
    int midterm, final;
} Student;

void write_student(FILE *fp, const char *tag, const Student *e, double score);

int scan_student(Student *e, const char *line);

enum {
    MAXSTUD = 10
};

int main(void) {
    char line[4096];
    Student stu[MAXSTUD];
    FILE *f = fopen("grades.txt", "r");
    FILE *pa = fopen("passed.txt", "w");
    FILE *fa = fopen("failed.txt", "w");
    if (f == NULL || pa == NULL || fa == NULL) {
        perror("Error");
        return 1;
    }
    fprintf(fa, "First name Last name Midterm Final Overall\n");
    fprintf(pa, "First name Last name Midterm Final Overall\n");
    if (fgets(line, sizeof(line), f) == 0)
        return 1;
    for (int i = 0; i < MAXSTUD && fgets(line, sizeof(line), f) != 0; i++) {
        if (scan_student(&stu[i], line) == 0) {
            if (stu[i].midterm * 0.4 + stu[i].final * 0.6 >= 50) {
                write_student(pa, "Student", &stu[i], stu[i].midterm * 0.4 + stu[i].final * 0.6);
            } else {
                write_student(fa, "Student", &stu[i], stu[i].midterm * 0.4 + stu[i].final * 0.6);
            }
        }
    }
    fclose(pa);
    fclose(fa);
    fclose(f);
    return 0;
}

int scan_student(Student *e, const char *line) {
    if (sscanf(line, "%24s %24s %d %d",
               e->first, e->last, &e->midterm, &e->final) != 4)
        return -1;

    return 0;
}

void write_student(FILE *fp, const char *tag, const Student *e, double score) {
    fprintf(fp, "%s %s %2d %2d %2d\n",
            e->first, e->last, e->midterm, e->final, (int) score);
}

测试

   $ cat grades.txt 
    First name Last name Midterm Final
    Ali Caliskan 60 40
    Veli Dalgaci 80 10
    Turkan Sevimli 90 50
    Ali Yilmaz 30 70
    Ahmet Koc 50 50⏎                                                                
    $./a.out
    $ cat passed.txt ;cat failed.txt 
    First name Last name Midterm Final Overall
    Turkan Sevimli 90 50 66
    Ali Yilmaz 30 70 54
    Ahmet Koc 50 50 50
    First name Last name Midterm Final Overall
    Ali Caliskan 60 40 48
    Veli Dalgaci 80 10 38