函数使用示例

读取

#include <stdio.h>
//成功返回流指针，失败返回空指针

int main(void)
{
        FILE *file;
        char filename[] = "./files/demo.txt";
        char mode[] = "r";
        file = fopen(filename,mode);
        if(file == NULL)
        {
                printf("无法打开文件\n");
                return 1;
        }
        int ch;
        while((ch = fgetc(file)) != EOF){
                printf("%c",ch);
        }
        //执行完毕后关闭流
        fclose(file);

        return 0;
}

使用 fgets 函数按行读取文件内容：

//成功返回流指针，失败返回空指针

int main(void)
{
        FILE *file;
        char filename[] = "./files/demo.txt";
        char mode[] = "r+";
        file = fopen(filename,mode);
        if(file == NULL)
        {
                printf("无法打开文件\n");
                return 1;
        }
        //int ch;
//      while((ch = fgetc(file)) != EOF){
//              printf("%c",ch);
//      }
        char buffer[1024];
        while(fgets(buffer,sizeof(buffer),file) != NULL)
        {
                printf("%s",buffer);
        }
        //执行完毕后关闭流
        fclose(file);

        return 0;
}

写入

#include <stdio.h>
int main(int argc,int*argv[])
{
        FILE *file;
        char filename[] = "./files/demo2.txt";
        char mode[] = "w";
        int ch;
        file = fopen(filename,mode);
        if(file == NULL)
        {
                printf("无法打开文件");
                return 1;
        }
        while((ch = getchar()) != EOF)
        {
                fputc(ch,file);
        }
        fclose(file);
        return 0;
}

#include <stdio.h>

int main(int argc,int* argv[])
{
        FILE* file;
        char filename[] = "./files/exxample.txt";
        char mode[] = "w";
        char str[100];

        file = fopen(filename,mode);
        if(file == NULL)
        {
                printf("无法打开文件.\n");
                return 1;
        }
        printf("请输入要写入的文件的字符串:\n");
        fgets(str,sizeof(str),stdin);
        fputs(str,file);

        fclose(file);
        return 0;
 }
        ```