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C语言文件处理

C语言文件处理

• fopen()：打开文件

  • 语法格式：FILE *fopen(const char *filename, const char *mode);
  • 示例：FILE *fp = fopen("data.txt", "r");

• fclose()：关闭文件

  • 语法格式：int fclose(FILE *stream);
  • 示例：fclose(fp);

• fscanf()：从文件读取格式化数据

  • 语法格式：int fscanf(FILE *stream, const char *format, ...);
  • 示例：fscanf(fp, "%d %s", &num, str);

• fprintf()：向文件写入格式化数据

  • 语法格式：int fprintf(FILE *stream, const char *format, ...);
  • 示例：fprintf(fp, "%d %s\n", num, str);

• fgetc()：从文件读取单个字符

  • 语法格式：int fgetc(FILE *stream);
  • 示例：int c = fgetc(fp);

• fputc()：向文件写入单个字符

  • 语法格式：int fputc(int c, FILE *stream);
  • 示例：fputc('A', fp);

• fgets()：从文件读取字符串

  • 语法格式：char *fgets(char *s, int size, FILE *stream);
  • 示例：fgets(buffer, 100, fp);

• fputs()：向文件写入字符串

  • 语法格式：int fputs(const char *s, FILE *stream);
  • 示例：fputs("Hello", fp);

• fread()：从文件读取二进制数据

  • 语法格式：size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream);
  • 示例：fread(buffer, sizeof(int), 10, fp);

• fwrite()：向文件写入二进制数据

  • 语法格式：size_t fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream);
  • 示例：fwrite(buffer, sizeof(int), 10, fp);

文件处理示例

文本文件读写示例

#include <stdio.h>

int main() {
    FILE *fp;
    char buffer[100];
    int num;
    
    // 写入文本文件
    fp = fopen("data.txt", "w");
    if (fp == NULL) {
        printf("Error opening file for writing\n");
        return 1;
    }
    
    fprintf(fp, "Hello, World!\n");
    fprintf(fp, "The answer is %d\n", 42);
    fclose(fp);
    
    // 读取文本文件
    fp = fopen("data.txt", "r");
    if (fp == NULL) {
        printf("Error opening file for reading\n");
        return 1;
    }
    
    printf("File content:\n");
    while (fgets(buffer, sizeof(buffer), fp) != NULL) {
        printf("%s", buffer);
    }
    fclose(fp);
    
    return 0;
}

二进制文件读写示例

#include <stdio.h>

struct Student {
    char name[50];
    int age;
    float score;
};

int main() {
    FILE *fp;
    struct Student s1 = {"John", 20, 85.5};
    struct Student s2;
    
    // 写入二进制文件
    fp = fopen("student.dat", "wb");
    if (fp == NULL) {
        printf("Error opening file for writing\n");
        return 1;
    }
    
    fwrite(&s1, sizeof(struct Student), 1, fp);
    fclose(fp);
    
    // 读取二进制文件
    fp = fopen("student.dat", "rb");
    if (fp == NULL) {
        printf("Error opening file for reading\n");
        return 1;
    }
    
    fread(&s2, sizeof(struct Student), 1, fp);
    printf("Student information:\n");
    printf("Name: %s\n", s2.name);
    printf("Age: %d\n", s2.age);
    printf("Score: %.1f\n", s2.score);
    fclose(fp);
    
    return 0;
}