【C++|code】C++中产生随机数和文件读写

开发平台：visual studio 2008

随机数：

产生随机数，每次产生的数字都不相同。

#include "stdafx.h"

#include<stdio.h>

#include<stdlib.h>//for scrand() & system()

#include<time.h>//for time()

int main(int argc, char* argv[])

{

srand((int)time(0));

for(int x=0;x<10;x++)

printf("%d\n",rand()%100);

system("PAUSE");//create a pause and waite for pressing any key

return 0;

}

文件读写：

#include "stdafx.h"

#include <stdio.h>

#include<stdlib.h>//for file-operating

int main(int argc, char* argv[])

{

FILE* fp=fopen("E:\\MPI\\textfileReadWrite\\Debug\\b.txt", "r");

char line[40] = {0};

if(fp)

{

//read a file

while(!feof(fp))

{

fscanf(fp, "%s", line);

printf("%s\n", line);

}

fclose(fp);//can't be forgoted.

//write into a file

//when open a file with 'w' mode,the content of the file was cleared.

FILE* fp2=fopen("E:\\MPI\\textfileReadWrite\\Debug\\b.txt", "w+");

fprintf(fp2,"%s\n","lab513@zhu");

fclose(fp2);

//read the file again

fp=fopen("E:\\MPI\\textfileReadWrite\\Debug\\b.txt", "r");

while(!feof(fp2))

{

fscanf(fp2, "%s", line);

printf("%s\n", line);

}

fclose(fp);

}

else

fclose(fp);

system("PAUSE");

return 0;

}

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snigoal@Wang,HUST.Wuhan.China