C语言“fread”函数的用法？

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C语言“fread”函数的用法？

C语言“fread”函数的用法为“size_tf read(void *buffer,size_t size,size_t count,FILE *stream)”，其作用是从一个文件流中读数据，读取count个元素，每个元素size字节。

示例1

复制代码#include <stdio.h>
#include <process.h>
#include <string.h>
int main()
{
	FILE *stream;
	char msg[]="this is a test";
	char buf[20];
	if ((stream=fopen("dummy.fil","w+"))==NULL)
	{
		fprintf(stderr,"cannot open output file.n");
		return 1;
	}
	/*write some data to the file*/
	fwrite(msg,1,strlen(msg)+1,stream);
	/*seek to the beginning of the file*/
	fseek(stream,0,SEEK_SET);
	/*read the data and display it*/
	fread(buf,1,strlen(msg)+1,stream);
	printf("%sn",buf);
	fclose(stream);
	system("pause");
	return 0;
}1
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#include <stdio.h>
#include <process.h>
#include <string.h>
int main()
{
	FILE *stream;
	char msg[]="this is a test";
	char buf[20];
	if ((stream=fopen("dummy.fil","w+"))==NULL)
	{
		fprintf(stderr,"cannot open output file.n");
		return 1;
	}
	/*write some data to the file*/
	fwrite(msg,1,strlen(msg)+1,stream);
	/*seek to the beginning of the file*/
	fseek(stream,0,SEEK_SET);
	/*read the data and display it*/
	fread(buf,1,strlen(msg)+1,stream);
	printf("%sn",buf);
	fclose(stream);
	system("pause");
	return 0;
}
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示例2

复制代码int main(void)
{
	FILE *stream;
	char list[30];
	int i,numread,numwritten;
	/*open file in text mode:*/
	if ((stream=fopen("fread.out","w+t"))!=NULL)
	{
		for (i=0;i<25;i++)
		{
			list[i]=(char)('z'-i);
		}
		/*write 25 characters to stram*/
		numwritten=fwrite(list,sizeof(char),25,stream);
		printf("Wrote %d itemsn",numwritten);
		fclose(stream);
	}
	else
		printf("Problem opening the filen");
        if ((stream=fopen("fread.out","r+t"))!=NULL)
        {
			numread=fread(list,sizeof(char),25,stream);
			printf("Number of items read =%dn",numread);
			printf("Contents of buffer=%.25sn",list);
			fclose(stream);
        } 
        else
        {
			printf("File could not be openedn");
        }
	system("pause");
	return 0;
}1
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int main(void)
{
	FILE *stream;
	char list[30];
	int i,numread,numwritten;
	/*open file in text mode:*/
	if ((stream=fopen("fread.out","w+t"))!=NULL)
	{
		for (i=0;i<25;i++)
		{
			list[i]=(char)('z'-i);
		}
		/*write 25 characters to stram*/
		numwritten=fwrite(list,sizeof(char),25,stream);
		printf("Wrote %d itemsn",numwritten);
		fclose(stream);
	}
	else
		printf("Problem opening the filen");
        if ((stream=fopen("fread.out","r+t"))!=NULL)
        {
			numread=fread(list,sizeof(char),25,stream);
			printf("Number of items read =%dn",numread);
			printf("Contents of buffer=%.25sn",list);
			fclose(stream);
        } 
        else
        {
			printf("File could not be openedn");
        }
	system("pause");
	return 0;
}
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