fread函數的用法(如何使用C語言“fread”函數)

C語言“fread”函數的用法為“size_tf read(void *buffer,size_t size,size_t count,FILE *stream)”,其作用是從一個文件流中讀數據,讀取count個元素,每個元素size字節。

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;i<25;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);}elseprintf("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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