Thread: String Problem

Hello, I have a fairly simple problem, that I can't seem to straighten out. Right now, I need to get two inputs, both strings, I can do that without a problem. The problem is, I need to extend the length of the second string input to match the length of the first, example

Before formatting..

1st Input: This is a test
2nd Input: Test

After formatting..

1st Input: This is a test
2nd Input: TestTestTestTe

See where I'm going? I've tried some methods, but they became over-elaborate, and obviously failed. Are there any simple solutions to this problem out there?

Thanks a lot

Using char arrays or std::string? I think it would be pretty easy using null-terminated char arrays. I imagine a for loop like this would be a good place to start:

Code:

for (int i=end_of_string2,j=0;i<length_of_string1;i++,j++)
{
  
}

(You could use strlen() to get the lengths of the strings)

Piece of cake if you're using the standard string class:

Code:

#include <iostream>
#include <string>

using namespace std;

int main() {
  string a = "This is a test";
  string b = "Test";
  string c;

  while (c.size() < a.size())
    c += b;
  c.resize(a.size());

  cout << a << '\n' << c << '\n';

  return 0;
}

It's not so easy with array based strings, but still not bad, you'd have to do it manually:

Code:

#include <iostream>
#include <cstring>

using namespace std;

int main() {
  char a[] = "This is a test";
  char b[] = "Test";
  size_t alen = strlen(a);
  size_t blen = strlen(b);
  char *c = new char[alen + 1];

  *c = '\0';
  while (strlen(c) < alen - blen)
    strcat(c, b);
  strncat(c, b, alen - strlen(c));

  cout << a << '\n' << c << '\n';

  return 0;
}

No biggie, but it's harder to get right than the first one.

Well if you're just going to give him a solution
Here's another way:

Code:

char a[50];
char b[50]={0};
std::cin.getline(a,50);
std::cin.getline(b,10);
int lenb = strlen(b);
int lena = strlen(a);
for (int i=lenb,j=lenb;i<lena;i++,j++)
   b[i] = b[j%lenb];

std::cout<<a<<std::endl;
std::cout<<b<<std::endl;

Although you'd want to check that lenb!=0

Yeah, I am using the string class for this. Thanks Narf! That's exactly what I was looking for, and it works fine.

Well if you're just going to give him a solution

Code is more expedient than a detailed explanation, especially with something trivial like this. Besides, I wasn't giving him the solution because he has to go to the effort of making sure that I'm not an idiot (ie. that the code works like it should) and integrating it into his program.