Start New Discussion within our Software Development Community

You can have fun and learn something too. Not too much fun though! Here we take a lighthearted look at C++ string, various ways to assign a string and substring, spell forward and reverse, find characters and substrings, append, insert, replace, remove characters, separate a sentence into words and more.

// testing std::string  
// a Dev-C++ challenged Console Application by  vegaseat  19dec2004

#include <iostream>
#include <string>

using namespace std;  // std::string

int main()
{
  int k, n;
  
  // assign a string
  string s1 = "What is the difference between roast beef and pea soup?";
  cout << s1 << endl << endl;
  
  // use \" for embedded double quotes
  string s2 =  "<tr><td><img src=\"naomi.bmp\"></td><td><b>"; 
  cout << s2 << endl << endl;
  
  // for a multiline assignment use \ to connect
  string s3 = 
  "If you tell a lie long enough\n\
  and often enough,\n\
  it becomes the truth!";
  cout << s3 << endl << endl;
  
  // assign a substring from source to target
  // starting at index = 8 and len = 3 characters long
  string target;
  string source = "No new taxes!";
  target.assign(source, 8, 3);
  cout << source << endl;  
  cout << target << endl;  // displays axe
  
  // spell out the above string
  string::const_iterator ai;
  // spell forwards
  for(ai = source.begin(); ai != source.end(); ai++)
  {
    cout << *ai << ' ';  // separate with a space
  }
  cout << endl;
  // spell in reverse
  for(ai = source.end() - 1; ai != source.begin() - 1; ai--)
  {
    cout << *ai << ' ';  // separate with a space
  }
  cout << endl << endl;
  
  // assign num = 50 characters '!' to a string
  string hey; 
  hey.assign(50,'!');
  cout << hey << endl;
  
  // append hey to source
  source.append(hey);
  cout << source << endl << endl;  

  // add marker
  for(k = 0, n = 0; k < 18; k++, n++)
  {
    if (n > 9) n = 0;
    cout << n;
  }
  cout << endl;  
  string text = "There was nobody at the Missing Persons' Bureau";
  cout << text << endl;
  // return the character at position 0 and 15 of text
  char ch = text.at(0);
  cout << "Character at position 0 = " << ch << endl;  
  ch = text.at(15);
  cout << "Character at position 15 = " << ch << endl; 
  // size() same as length()
  cout << "size = " << text.size() << "  capacity = " << text.capacity();
  cout << endl << endl;

  // copy num = 17 char of oldstr into newstr starting at index = 0
  string oldstr = "Frank is very fatherly!";
  // why not a little old stuff
  char newstr[80] = {0};
  oldstr.copy(newstr, 17, 0);
  cout << oldstr << endl;
  cout << newstr << endl << endl;

  // add marker
  for(k = 0; k < 10; k++)
  {
    cout << k;
  }
  cout << endl;
  // removes num = 6 characters from the current string
  // starting at index = 23
  string sd("A really stupid person never becomes senile!");
  cout << sd << endl;
  sd.erase(23, 6 );
  cout << sd << endl << endl;

  // return first occurrence of "stupid" within the current string 
  // starting at index = 0, string::npos (-1) if nothing is found
  int pos = sd.find( "stupid", 0 );
  if ( pos != string::npos )
  {
    cout << "stupid is at index " << pos;
  }
  else
  {
    cout << "Didn't find stupid";
  }
  cout << endl;
  
  // doing a reverse search from index, string::npos = fail (-1)
  pos = sd.rfind( "smart", 15 );
  cout << "smart is at index " << pos << " (fail=-1)" << endl << endl;

  // inserts str2 into str1 at locations 11 and then 20
  string str1 = "Judges live on income";
  string str2 = " fixed";
  str1.insert(11, str2);
  str1.insert(20, str2);
  cout << str1 << endl;
  // add ! to the end
  str1.push_back('!');
  cout << str1 << endl << endl;    

  // replace characters of tooth string with num (here length) 
  // characters from teeth string, beginning at index 21
  string tooth = "He ate it all with a toothpick";
  cout << tooth << endl;
  string teeth = "teethpick";
  tooth.replace( 21, teeth.length(), teeth );
  cout << tooth << endl << endl;

  // return a substring of a string starting at index = 19
  string str("They will greet us with flowers!");
  string sub = str.substr(19);
  cout << "original string      : " << str << endl;
  cout << "substring from 19 on : " << sub << endl;
  // change the size of string to num = 18 characters
  str.resize(18);
  cout << "resize to 18 char    : " << str << endl;
  // dito, but pad excess (here past 18) with char '!'
  str.resize(21,'!');
  cout << "resize with ! padding: " << str << endl << endl;

  // swap strings
  string first( "one, uno, eins, interesting lines" );
  string second( "two, dos, zwei, cake-flavored pie" );
  cout << "Before swap:" << endl;
  cout << "first =  " << first << endl;
  cout << "second = " << second << endl << endl;  
  first.swap( second );
  cout << "After swap:" << endl;
  cout << "first =  " << first << endl;
  cout << "second = " << second << endl << endl;
  
  // use at() and substr() to separate a string s1 into words
  cout << s1 << endl << endl;  // show s1 in case you forgot
  int start = 0;
  // add a space to the end of s1 since this is our delimiter
  // this allows us to catch the last word properly
  s1.push_back(' ');
  for(k = 0; k < s1.size(); k++)
  {
    // found a space now show the word before that
    if (s1.at(k) == ' ')
    {
      // substr(startposition, length)
      cout << s1.substr(start, k - start) << endl;
      // update to new startposition
      start = k + 1;   
    }
  }
  cout << endl;
  
  cout << "Anyone can roast beef!" << endl;
 
  cin.get();   // wait
  return 0;
}
The article starter has earned a lot of community kudos, and such articles offer a bounty for quality replies.