Read/Write file in c++

[sheriff]

Dear friends,

im a newbee for this forum and c++ im doing my MSc in Simulation Tech in mech. Engineering. My knowledge of c++ is very little which I had during my UG studies Long long ago .I am now forced to do some programming as a small part of my thesis work. Here goes my task and question.

I want to read the text file and jus find the displacement old value and replace them with new value and write them in another file.........(I n my analysis, an input file has been created contains some variables.For ex: a displacement value the the only variable for several analysis which i need to change to perform different analysis)

Jus I made a small program for it by using all my C++ knowledge (!!!!!!!)

To replace 0.000(old value) to 1.413(new value) and write it in another file .

I didn’t use getline () function as it is trying to replace the whole line at once even if there r two values to replace within a line.

I donno whether it is possible using getline function(I didn’t succeed replacing all the values in a line by using it)


Here comes my text file

Samp1.txt: contains

0.000 God save us programmers

I don’t do programming here after 0.000 for sure 0.000



[CODE=c]#include <fstream>
#include <iostream>
#include <string>
using namespace std;

int main()
{
string a;
string string1;
string string2 = "1.413";
string string3 = "0.000";

fstream inputFile("C:\\ TEMP\\samp1.txt ");
fstream outputFile;
outputFile.open ("C:\\TEMP\\sam p2.txt");

while (!inputFile.eof ()) {
inputFile >> a;
//cout << a ;
int spot = a.find(string2) ;

if (spot >= 0) {
cout << "found at" << spot << " the string" << string2 << endl;
string1 = a;
int b = string3.length( );
string1.replace (spot, b, string3);
a = string1;
cout << a << endl;
cin.get();
}
outputFile << a << endl;

}
outputFile.clos e();
}
[/CODE]
Output:
Samp2.txt: written file contains output like

1.413
God
save
us
programmers
I
don’t
do
programming
here
after
1.413
for
sure
1.413
1.413 (****)


1. I want to hav my output file looks the same as my input file (only with a change of value replacement) not like this now I hav
2. while loop executes eof () true value at the end of file and prints again the value “a” (which stored last …. refer output (****))


may b sound simple and sillyfor u, but for me its complex

i want my output looks like

Samp2.txt:

1.413 God save us programmers

I don’t do programming here after 1.413 for sure 1.413


Will you give me some sugesstion to get my output in such a manner?

some new functions or methods?

[Savage]

Problem is probably here:

inputFile >> a;

this extractor will input data in string a until reaching a whitespace.

Try using getline()

Savage

[sheriff]

Problem is probably here:

inputFile >> a;

this extractor will input data in string a until reaching a whitespace.

Try using getline()

Savage

Thx savage

as i mentioned earlier, by using getline() function i hav not succeed

can u tell me how can i replace a particular string from a line

int main()
{
string a;
string string1;
string string2="0.000" ;
string string3="1.413" ;
string line;
fstream inputFile("C:\\ TEMP\\samp1.txt ");
fstream outputFile;
outputFile.open ("C:\\TEMP\\sam p2.txt");
while(!inputFil e.eof())
{
//inputFile >> a;
getline(inputFi le, line);
cout << line <<endl;

cout <<"line is "<< line << endl;
cin.get();
int spot = line.find(strin g2);

if(spot >= 0)
{
cout<<"found at"<<spot<<" the string" <<string2<<endl ;
// string1 = line;
int b=string3.lengt h();
line.replace(sp ot, b, string3);
//line = string1;

}
outputFile<< line<<endl;
//cout<< line <<"is written"<<endl;
//cin.get();
}
outputFile.clos e();
}

For ex:
my input file contains:

God, save us 0.000 programmers 0.000

i want the output as

God, save us 1.413 programmers 1.413

but the output is
God, save us 1.413 programmers 0.000

whethe i need to use any loop within a line?

[Savage]

Yes,u do need to use a do while loop,like:

int spot;

do{

	spot = line.find(string2);

	if(spot >= 0)
	{
		cout<<"found at"<<spot<<" the string" <<string2<<endl;
		// string1 = line;
		int b=string3.length();
		line.replace(spot, b, string3);
		//line = string1;

	}
}while(spot<=line.length());

Savage

[sheriff]

Yes,u do need to use a do while loop,like:

int spot;

do{

	spot = line.find(string2);

	if(spot >= 0)
	{
		cout<<"found at"<<spot<<" the string" <<string2<<endl;
		// string1 = line;
		int b=string3.length();
		line.replace(spot, b, string3);
		//line = string1;

	}
}while(spot<=line.length());

Savage

thx much savage i did the same

[Savage]

thx much savage i did the same

Glad to help!

Savage