Read Lines from a file and split each one

[Wh1t3w0lf]

Hi

I am new to C++ and I want to write a programm that reads lines from a file into character arrays and then splits them (the arrays) into two parts. The first part is before the delimeter (usually " ") and the second after it. The file is consisted of eleven lines. The first is a number that must be stored in a k variable. The 10 remaining have 2 numbers each and the numbers are divided by a space (" ")
e.g
---Start of file-----
5
2 12
3 45
1 20
5 34
7 29
8 84
10 28
9 14
---End of file-----

Total eleven lines

Here's how I think the code should be. Please help me fill in the missing parts of the loop


int k;
ifstream b_file("input.txt");
b_file>>k;
//The above part reads the first number and stores it in k var


for (i=1; i<=10; i++)
{
//The code in here must input Line of file into Line[i] string
//the code in here must split Line[i] into TempA[i] (this is the first number of the line) and TempB[i] (this is the second number of the line) with " " as the delimeter
}
b_file.close();


Thanks for your help

Wh1t3w0lf

[CornedBee]

I'm not familiar with the c++ file streams. If you don't need the string really, it is easy:

for (i=1; i<=10; i++) 
{ 
   b_file >> TempA[i] >> TempB[i];
}

But if you really need the string it gets trickier:

char Line[10][10];  // 10 strings of 10 characters each
char* secNum;  // pointer to the second number

for (i=1; i<=10; i++) 
{ 
//The code in here must input Line of file into Line[i] string 
  b_file >> Line[i];
// the code in here must split Line[i] into TempA[i] (this is the first // number of the line) and TempB[i] (this is the second number of // the line) with " " as the delimeter 
  TempA[i] = atoi(Line[i]);  // first number
  secNum = strtok(Line[i], " ");  // find space
  TempB[i] = atoi(secNum);  // second number
}

[Wh1t3w0lf]

I tested this:

#include <iostream.h>
#include <fstream.h>
#include <string.h>
#include <stdlib.h>


main()
{
char Line[10][10]; // 10 strings of 10 characters each
char* secNum; // pointer to the second number

int k;
ifstream b_file("input.txt");
b_file>>k;
int i;
char TempA[10];
char TempB[10];

for (i=1; i<=10; i++)
{

b_file >> Line[i];
TempA[i] = atoi(Line[i]); // first number
secNum = strtok(Line[i], " "); // find space
TempB[i] = atoi(secNum); // second number
cout<<"First Number: "<< TempA[i] <<" second number: "<<TempB[i];
}
b_file.close();

return 0;
}


And the output I get is wrong. It keeps printing various characters instead of the ones that it should print.
Also I need the two numbers of each line (I don't just want to print them- I did it as a test to see if it works)

[parksie]

char is interpreted by iostreams as a character, cast them to an int before inserting them:

cout<<"First Number: "<< (int)TempA[i] <<" second number: "<< (int)TempB[i];

[Wh1t3w0lf]

None of these workes. Anyway I sat and wrote a custom made routine for this $#^% Here it is

ifstream b_file("input.txt");
b_file>>k;

for (i=1; i<=20; i++)
b_file >> number[i];
for (i=1; i<=10; i++)
{
first[i]=atoi(number[2*i-1]);
second[i]=atoi(number[2*i]);
}
b_file.close();


So now we have the 10 first numbers in first[i] (i 1 to 10)
and the 10 second number in second[i] (i 1 to 10)


I want to thank you guys for helping me.

Wh1tew0lf

P.S By the way strings in C++ SUCK!!!

[parksie]

Originally posted by Wh1t3w0lf
P.S By the way strings in C++ SUCK!!!

You mean C

Neither C or C++ has intrinsic string handling capability - it's not part of the design, since they introduce inefficiencies. However, C++ has the string class as part of the Standard Library, which you should (to be correct) use instead of character arrays.

[CornedBee]

Well, I'm sorry if my functions didn't work (did you try the first one? Judging from your own solution you wouldn't need the extended features of the second.), but in any case, make sure that you start the array indizes at 0, not at 1 like in VB. You'll a) waste memory and b) will get weird results (access violations etc.) when you try to make a 20 integer array (int ar[20]) and then want to access the last member (ar[19] would be correct, but ar[20] would be the VB way).

[Wh1t3w0lf]

damn...didn't know about the string class

CornedBee your functions are proly correct but I'm such a n00b (or lamo) and I can't make them work.... Anyway thanks for your help.

Wh1t3w0lf