如何使用以C语言的文件操作函数？

[hcwsdiy]

我的问题是，使用C语言输入一组数据到一个文件中，
1首先输入文件名：
2然后共输入有多少组数据要输入：
3依次输入数据：
4最终，将数组的总个数赋给一个变量和将每组数据的第二个数（下面举例中的2,4,6,-9,0）赋给一个数组，输出数组里的值！
如：
input.txt
5
1 2
3 4
2 6
3 -9
5 0


以下这个程序，我已经完成了1,2,3步，请各位帮我实现第4步，谢谢！！！！
#include "stdio.h"
#include "stdlib.h"
void main()
{
FILE *fp;
char filename[10];
int n,i,x,y;
printf("input the file name:");
scanf("%s",filename);
if((fp=fopen(filename,"w"))==NULL)
{
printf("cannot open the file!\n");
exit(0);
}

scanf("%d",&n);
fprintf(fp,"%d\n",n);
for(i=0;i<n;i++)
{scanf("%d %d",&x,&y);
fprintf(fp,"%d %d\n",x,y);
}
}

[冰矿]

如果按你所说的话，没组两个数字，那很容易

#include <stdio.h>
int main()
{
    FILE *fp;
    char filename[10];
    char a[20];
    int n,i,x,y;
    printf("input the file name:");
    scanf("%s",filename);
    if ((fp=fopen(filename,"w"))==NULL)
    {
       printf("cannot open the file!\n");
       exit(0);
    }
    scanf("%d",&n);
    fprintf(fp,"%d\n", n);
    for (i = 0; i < n; i++)
    {
        scanf("%d %d",&x,&y);
        fprintf(fp,"%d %d\n",x,y);
    }
    fclose(fp);

    fp = fopen(filename,"r");
    for (i = 0; i < n; i++)
    {
         if (i == 0)
             fscanf(fp, "%d", &x);
         else
         {
             fscanf(fp, "%d %d", &x, &a[i-1]);
             printf("%d ",a[i-1]);
         }
    }
    fclose(fp);
    system("PAUSE");
    return 0;
}

[wudeshou82666]

#include <stdio.h>
#include <stdlib.h>
#include "stdafx.h"
int main()
{
FILE *fp;
char filename[10];
int n,i,x,y;
int a[][2];
printf("input the file name:");
scanf("%s",filename);
if((fp=fopen(filename,"w"))==NULL)
{
printf("cannot open the file!\n");
exit(0);
}

scanf("%d",&n);
fprintf(fp,"%d\n",n);
for(i=0;i <n;i++)
{scanf("%d %d",&x,&y);
fprintf(fp,"%d %d\n",x,y);
a[i][0]=x;a[i][1]=y;
}
for(int j=0;j<i;j++)
{
printf("%d\n",a[j][1]);
}
fclose(fp);
fp=NULL;
}
不一定对.大体上可以这样写吧

[waizqfor]

改了一下 LZ看看

#include "stdio.h" 
#include "stdlib.h" 
void main() 
{ 
FILE *fp; 
char num[20];
char filename[10]; 
int n,i,x,y; 
printf("input the file name:"); 
scanf("%s",filename); 
if((fp=fopen(filename,"w"))==NULL) 
  { 
  printf("cannot open the file!\n"); 
  exit(0); 
  } 

  scanf("%d",&n); 
    fprintf(fp,"%d\n",n); 
  for(i=0;i <n;i++) 
  {scanf("%d %d",&x,&y); 
  fprintf(fp,"%d %d\n",x,y); 
  } 
   fclose(fp);
fp = fopen(filename,"r");
for (i=0;i<n;i++)
{
if (i==0)
fscanf(fp, "%d", &x);
else
{
   fscanf(fp, "%d %d", &x, &num[i-1]);
   printf("%d ",num[i-1]);
}
}
fclose(fp);
}

[riceli]

#include <stdlib.h>
#include <stdio.h>
#define ERR_NO_FILED			0
#define ERR_OVER_MAX			1
#define ERR_NO_FILE			2
char* g_szError[] = 
{
	"未进行赋值!",			/*0*/
	"超过最大允许的行数!",		/*1*/
	"不能打开文件!"
};
void OutError(int num)
{
	printf("%s\n", g_szError[num]);
}
#define MAX_LINE_NUM	20	/*最大20行*/
int Example()
{
	int nLine = 0;				/*实际输入多少行*/
	int* parLine = NULL;			/*指向输入字符数组的指针*/
	int i = 0;
	FILE* fp;
	char szFileName[256];
	int* pNum = NULL;

	printf("请输入文件名:\n");
	scanf("%s", szFileName);	
	printf("文件名:%s\n", szFileName);
	printf("请输入总行数:\n");
	while(1)
	{
		scanf("%d", &nLine);	
		if (nLine <= MAX_LINE_NUM)
		{
			break;
		}
		OutError(ERR_OVER_MAX);
	}

	parLine = (int*)malloc(nLine * sizeof(int) * 2);	/*申请空间*/

	for (i = 0; i < nLine; i++)
	{
		scanf("%d %d", parLine + 2 * i, parLine + 2 * i + 1);	
	}

	fp = fopen(szFileName, "w");
	if (NULL == fp)
	{
		OutError(ERR_NO_FILE);
		goto PROG_END;
	}
	fprintf(fp, "%d\n", nLine);
	for (i = 0; i < nLine; i++)
	{
		fprintf(fp, "%d %d\n", *(parLine + 2 * i), *(parLine + 2 * i + 1));
	}
	
	fclose(fp);
	fp = NULL;
	printf("读入完毕!");
	

PROG_END:
	free(parLine);
	parLine = NULL;
	system("PAUSE");
	return 1;
}

[dongpy]

#include "stdio.h"
#include "stdlib.h"
void main()
{
FILE *fp;
char filename[10];
int data[32];
int n,i,x,y;
printf("input the file name:");
scanf("%s",filename);
if((fp=fopen(filename,"w"))==NULL)
{
printf("cannot open the file!\n");
exit(0);
}

scanf("%d",&n);
fprintf(fp,"%d\n",n);
for(i=0;i <n;i++)
{scanf("%d %d",&x,&y);
fprintf(fp,"%d %d\n",x,y);
data[i] = y;
}

for(i=0;i <n;i++)
{
printf( "%d ", data[i] );
}
}

[thesecretblue]

同上！！！！

[thinkboy234]

仅供参考：

#include "stdio.h" 
#include "stdlib.h" 
void main() 
{ 
	FILE *fp; 
	char filename[10]; 
	int n,i,x,y; 
	printf("input the file name:"); 
	scanf("%s",filename); 
	if((fp=fopen(filename,"w"))==NULL) 
	{ 
		printf("cannot open the file!\n"); 
		exit(0); 
	} 
	
	scanf("%d",&n); 
    fprintf(fp,"%d\n",n); 
	for(i=0;i <n;i++) 
	{
		scanf("%d %d",&x,&y); 
		fprintf(fp,"%d %d\n",x,y); 
	} 
	fclose(fp);

	fp=fopen(filename,"r");
	fscanf(fp, "%d", &x);
	i=0;
	i++;
	while(i<n)
	{
		fscanf(fp, "%d %d", &x, &num[i-1]);
		printf("%d ",num[i-1]);
	}
	fclose(fp);
}

[thinkboy234]

while(i<n)
{
fscanf(fp, "%d %d", &x, &num[i-1]);
printf("%d ",num[i-1]);
i++; //改一下这
}

可能还有差的地方。

[猫已经找不回了]

接分帮顶.

[hcwsdiy]

你的程序有一点错误，经x的值被覆盖了，i<n应改为i<=n,谢谢你的帮助！！！
for (i = 0; i < n; i++)
{
if (i == 0)
fscanf(fp, "%d", &x);
else
{
fscanf(fp, "%d %d", &x, &a[i-1]);
printf("%d ",a[i-1]);
}
}
fclose(fp);
system("PAUSE");
return 0;
}

[hcwsdiy]

你的程序有一点错误，经x的值被覆盖了，i<n应改为i<=n,谢谢你的帮助！！！
for (i = 0; i < n; i++)
{
if (i == 0)
fscanf(fp, "%d", &x);
else
{
fscanf(fp, "%d %d", &x, &a[i-1]);
printf("%d ",a[i-1]);
}
}
fclose(fp);
system("PAUSE");
return 0;
}