待讀入文件

1.greenteemo

2.csdn

3.blog

代碼，詳細說明見注釋

#include #define LENGTH_OF_LINE 1024

int main(){

FILE *fp = fopen("file.txt", "r"); // 打開文件

char line[LENGTH_OF_LINE];

while( fgets(line, LENGTH_OF_LINE, fp) ){

printf("%s\n", line); // 讀取文件內容

}

// back to beginning of file

// 當前文件指針指向文件末尾

printf("=== back to beginning of file ===\n");

rewind(fp); // 回到文件最開頭

fgets(line, LENGTH_OF_LINE, fp); // 讀入第一行，此時文件指針指向第二行開頭

printf("current line : %s\n", line);

// back to beginning of line

printf("=== back to beginning of line ===\n");

fgets(line, LENGTH_OF_LINE, fp); // 讀入第二行，此時文件指針指向第三行開頭

long offset = ftell(fp); // 記錄第三行開始的位置與文件開頭的偏置值

fgets(line, LENGTH_OF_LINE, fp); // 讀入第三行，此時文件指針指向文件末尾

printf("current line :%s\n", line);

fseek(fp, offset, SEEK_SET); // 根據offset回到第三行開頭

fgets(line, LENGTH_OF_LINE, fp); // 讀入第三行，此時文件指針指向文件末尾

printf("current line :%s\n", line);

return 0;

}

輸出

1.greenteemo

2.csdn

3.blog

=== back to beginning of file ===

current line : 1.greenteemo

=== back to beginning of line ===

current line :3.blog

current line :3.blog