C语言“fread”函数的用法？「建议收藏」

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 

#include 

#include 

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);

    }

    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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