Question

C++写一个程序：打开指定文本文件，在每一行前加行号

Answer 1

#include <stdio.h>
#include <string.h>
#define BUFF_SIZE 50
int main()
{
char file[256],buff[BUFF_SIZE+1];
FILE* fin = NULL;
int bL = 1;
int iLN = 0; // line number

printf("Enter file path and name:");
scanf("%s",file);

if (NULL == (fin = fopen(file,"r")))
{
printf("file open error. \n");
return -1;
}

while (NULL != fgets(buff,BUFF_SIZE,fin))
{
if (bL) printf("%3d:%s",++iLN,buff);
else printf("%s",buff);
if (buff[strlen(buff)-1] == '\n') bL = 1;
else bL = 0;
}
fclose(fin);
}

Answer 2

#include<iostream>
#include<fstream>
using namespace std;

void main() {
ofstream file;
file.open("input.txt");
file<<"aaaaaaaa\nbbbbbbbb\ncccccccc";
file.close();

ifstream filei("input.txt");
ofstream fileo;
fileo.open("output.txt");

char c;
filei>>noskipws;
int i=1;
fileo<<i<<".";
cout<<i<<".";
while(filei>>c) {
if(c=='\n') {
i++;
fileo<<"\n";
cout<<"\n";
fileo<<i<<".";
cout<<i<<".";
} else {
fileo<<c;
cout<<c;
}
}
filei.close();
fileo.close();
}

Answer 3

程序如下：

#include <stdio.h>
#include <string.h>
#define BUFF_SIZE 50
int main()
{
char file[256],buff[BUFF_SIZE+1];
FILE* fin = NULL;
int bL = 1;
int iLN = 0; // line number

printf("Enter file path and name:");
scanf("%s",file);

if (NULL == (fin = fopen(file,"r")))
{
printf("file open error. \n");
return -1;
}

while (NULL != fgets(buff,BUFF_SIZE,fin))
{
if (bL) printf("%3d:%s",++iLN,buff);
else printf("%s",buff);
if (buff[strlen(buff)-1] == '\n') bL = 1;
else bL = 0;
}
fclose(fin);
}

Answer 4

答案不是C的，我也想问