示例：向文件中写入读取单词

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX 41

int main(int argc, char* argv[])
{
	FILE *fp;
	char words[MAX];

	if ((fp = fopen("wordy", "a+")) == NULL)
	{
		fprintf(stdout, "Can't open \"wordy\" file.\n");
		exit(EXIT_FAILURE);
	}

	puts("Enter words to add to the file; press the #");
	puts("key at the beginning of a line to terminate.");
	while ((fscanf(stdin, "%40s", words) == 1) && (words[0] != '#'))
		fprintf(fp, "%s\n", words);

	puts("File contents:");
	rewind(fp); // 返回到文件开始处
	//从文件指针中读取1个单词存放到words中
	while (fscanf(fp, "%s", words) == 1)
		puts(words);
	puts("Done!");
	if (fclose(fp) != 0)
		fprintf(stderr, "Error closing file\n");

	system("pause");
	return 0;
}

运行测试

再次运行