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[英]C programming: How to extract a particular column from an input file and store in an array
[英]Reading input from file and store in an array in a particular format in C
我想从文本文件中读取并显示一些输出
输入文件格式:
0 0 3
0 1 2
1 3 4
2 1 4
3 2 3
3 1 2
4 3 4
每行的第一位数字表示特定的一天(第0天到第4天),每行的第二位和第三位数字表示当天发送信息的演员。 我编写了以下c代码来每天显示参与的演员:
我的示例代码:
#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#define B 5 // number of days
#define A 5 // number of total actors
main()
{
FILE *fp;
int end = 0;
int day1, day, i, j, k1, k2;
int esin[A][A];
for (i = 0; i < A; i++) // initializing array
{
for (j = 0; j < A; j++)
{
esin[i][j] = 0;
}
}
fp = fopen("test.txt", "r"); // the file contains the input
if (fp == NULL)
{
printf("\nError - Cannot open the designated file\n");
}
while (end == 0)
{
fscanf(fp, "%d", &day);
day1 = day; // day1 for comparing
while (day1 == day)
{
if (feof(fp))
{
end = 1;
break;
}
fscanf(fp, "%d %d", &k1, &k2);
esin[k1][k2] = 1;// edge creation
esin[k2][k1] = 1;// edge creation
fscanf(fp, "%d", &day);
}
printf("\nday: %d", day1); // for printing output of a particular day
for (i = 0; i < A; i++)
{
for (j = 0; j < A; j++)
{
if (esin[i][j] == 0)
continue;
else
printf("\n%d and %d have an edge", i, j);
}
}
for (i = 0; i < A; i++)
{
for (j = 0; j < A; j++)
{
esin[i][j] = 0;
}
}
}
}
但是我没有得到实际的输出。 例如,我想获得类似以下的输出:
day 0
0 and 3 have an edge
1 and 2 have an edge
day 1
3 and 4 have an edge
day 2
1 and 4 have an edge
day 3
2 and 3 have an edge
1 and 2 have an edge
day 4
3 and 4 have an edge
但是我不明白这一点。 我正进入(状态:
day 0
0 and 3 have an edge
1 and 2 have an edge
day 3
4 and 2 have an edge
day 4
3 and 2 have an edge
day 3
1 and 2 have an edge
day 3
4 and 2 have an edge
上面的代码有什么问题吗? 我需要进行哪些更正才能获得上述类似的输出?
在这条线
if(esin[i][j]=0)
您正在分配,但您想比较:
if(esin[i][j] == 0)
将if(esin[i][j]=0)
更改为if(esin[i][j]==0)
。
如果您这样做:
esin[k1][k2] = 1; esin[k2][k1] = 1;
输出将是第0天:
day: 0
0 and 3 have an edge
1 and 2 have an edge
2 and 1 have an edge
3 and 0 have an edge
只是做esin[k1][k2] = 1;
如果要输出如下:
day: 0
0 and 3 have an edge
1 and 2 have an edge
while(day1 == day)
循环内,另一个在该循环外)。 您可以尝试以下方法: bool first = true; while(end==0) { // Only first time we'll read 'day', // later we won't need this fscanf since there is another fscanf for reading day if(first) { fscanf(fp, "%d", &day); } day1 = day; //day1 for comparing first = false; while(day1 == day) { if (feof(fp)) { end=1; break; } fscanf(fp, "%d %d", &k1, &k2); esin[k1][k2] = 1;//edge creation fscanf(fp, "%d", &day); } ... }
在这里,您将从输入中扫描一个日期,并针对下一行的第一个整数(即日期)进行检查,当day1!= day时,您的内部循环将不会执行,但您已经读取了该天的值。 现在,当您在输入上执行fscanf(fp,“%d”,&day)时,它将读取人员ID(第二列),并且完全搞砸了。
我建议做一次文件扫描并建立图形
int a,b;
for (int i=0; i<5; i++)
for (int j=0; j<5; j++)
esin[i][j] = -1; // No edge
while (!feof(fp)) {
fscanf(fp, "%d %d %d", &day, &a, &b);
esin[a][b] = day;
esin[b][a] = day;
}
// for each day find person1,person2
for (int i=0; i<5; i++) {
printf("Day %d:\n", i);
for (int p=0; p<5; p++) {
for (int q=0; q<5; q++) {
if(esin[p][q] == i) {
printf ("%d and %d have an edge\n", p, q);
}
}
}
}
您可以投反对票,但我要求您发表评论,以便我改善此答案的质量
如果您只想用漂亮的英语打印输入内容[与输入文件的顺序相同]
这个简化的代码将这样做:
#include <stdio.h>
#include <stdlib.h>
#define B 5 // number of days
#define A 5 // number of total actors
int main()
{
int day1=-1, day, k1, k2;
FILE *fp= fopen("test.txt", "r"); // the file contains the input
if (fp == NULL)
{
printf("\nError - Cannot open the designated file\n");
return 0;
}
while(fscanf(fp,"%d%d%d",&day,&k1,&k2)>0)
{
if(day1!=day || day1==-1 )
printf("\nday: %d", day1=day);
printf("\n%d and %d have an edge", k1,k2);
}
return 0;
}
Buttttt如果您真的要存储每一天的输入,然后以字典方式[ACTOR NO.ASCENDING ORDER NO。]进行打印,则这里是经过修改的代码:
#include <stdio.h>
#include <stdlib.h>
#define B 5 // number of days
#define A 5 // number of total actors
int main()
{
int day1=-1, day, i, j, k1, k2;
int esin[A][A]={0};
FILE *fp= fopen("test.txt", "r"); // the file contains the input
if (fp == NULL)
{
printf("\nError - Cannot open the designated file\n");
return 0;
}
while(!feof(fp))
{
if( fscanf(fp,"%d%d%d",&day,&k1,&k2)<0 || (day1!=-1 && day1!=day ))
{
printf("\nday: %d", day1<0?day:day1);
for(i=0;i<A;i++)
for(j=0;j<A;esin[i][j]=0,j++)
if(esin[i][j])
printf("\n%d and %d have an edge", i, j);
esin[k1][k2]=1;
day1=day;
}
if(day1==-1)
day1=day;
esin[k1][k2]=1;
}
return 0;
}
reset
或initialize to zero
。 成员初始化程序{0}
或嵌套for for(j=0;j<A;esin[i][j]=0,j++)
循环的打印都可以这样做。 if(esin[i][j])
是指if(esin[i][j]!=0)
即演员i
消息演员j
。 PS编写短代码是一种好习惯,但令人毛骨悚然的代码不是...
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