C语言“fread”函数的用法？

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

#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;
}
    

示例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;
    i25;
i++)		{
    			list[i]=(char)('z'-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;
}
    

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