How to use the 'fread' function in C language?

Guanhui
Release: 2020-07-24 15:09:07
Original
6180 people have browsed it

How to use the 'fread' function in C language?

#How to use the "fread" function in C language?

The usage of the "fread" function in C language is "size_tf read(void *buffer,size_t size,size_t count,FILE *stream)". Its function is to read data from a file stream. Take count elements, each element is size bytes.

Example 1

#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("%s\n",buf);
	fclose(stream);
	system("pause");
	return 0;
}
Copy after login

Example 2

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)(&#39;z&#39;-i);
		}
		/*write 25 characters to stram*/
		numwritten=fwrite(list,sizeof(char),25,stream);
		printf("Wrote %d items\n",numwritten);
		fclose(stream);
	}
	else
		printf("Problem opening the file\n");
        if ((stream=fopen("fread.out","r+t"))!=NULL)
        {
			numread=fread(list,sizeof(char),25,stream);
			printf("Number of items read =%d\n",numread);
			printf("Contents of buffer=%.25s\n",list);
			fclose(stream);
        } 
        else
        {
			printf("File could not be opened\n");
        }
	system("pause");
	return 0;
}
Copy after login

Recommended tutorial: "PHP"

The above is the detailed content of How to use the 'fread' function in C language?. For more information, please follow other related articles on the PHP Chinese website!

Related labels:
c
source:php.cn
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template