Member Avatar for anuj_sharma 
#include<iostream>
#include<conio.h>
#include<string.h>
using namespace std;
int main()
{
    char ch;
    do
    {
      char str[80];
      cout<<"\nEnter The String\n";
      gets(str);
      int len=strlen(str);
      for(int i=0;i<len;i++)
      cout<<str[i];
      cout<<"\nContinue?\n";
      cin>>ch;
   }
    while(ch=='y' || ch=='Y');
   getch();
   return 0;
 }

On executing the above program, the loop asks "Continue?" only once and after that it skips the whole code in the do-while loop and goes to the statement of "Continue?". Please tell me what is the mistake??

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  • Latest Post Latest Post by anuj_sharma

Dani AI

Generated

Brief expert note: posted a classic input-mixing problem and correctly pointed toward using line-oriented input. Below are safer, portable alternatives and a couple of quick fixes that avoid the pitfalls in the original 2010 snippet.

A modern, robust pattern is to use C++ strings and std::getline for all line input. This keeps the input state predictable and avoids manual buffer management. Example pattern (reads the main line and the "continue" answer as lines, then tests the first character):

#include <iostream>
#include <string>

int main() {
    std::string text, answer;
    do {
        std::cout << "Enter the string:\n";
        if (!std::getline(std::cin, text)) break;
        std::cout << text << '\n';
        std::cout << "Continue? (y/n): ";
        if (!std::getline(std::cin, answer)) break;
    } while (!answer.empty() && (answer[0] == 'y' || answer[0] == 'Y'));
}

If keeping operator>> for a single-character reply, consume the rest of the input line afterwards so the next line read is fresh. The usual technique is std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); (requires <limits>). Another small trick is to use the std::ws manipulator before a getline to skip leading whitespace.

Two cautions: gets is unsafe and was removed from C (see the reference for gets), so prefer std::getline or safe C alternatives. Also avoid nonstandard headers like conio.h for portable code. For reference see std::getline and std::basic_istream::ignore on cppreference: gets, std::getline, ignore.

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Member Avatar for mike_2000_17

The problem is that calling "cin >> ch;" will wait for the enter to be pressed, then will read the first char. This will leave the newline or '\n' character on the input stream, so the next time you do gets() to read the line, it will grab the '\n' on the input stream and assume a line was entered. Since the str is empty (or only \n), it will output an extra newline before asking to continue, and again the same cycle repeats. You should use something that will get the '\n' character in the "Continue?" prompt, not a single char. For example, this will work (I don't have conio.h so I have removed those, and you probably should too because it is not standard or portable):

char str[80];
    do
    {
      cout<<"\nEnter The String\n";
      cin.getline(str,80);
      int len=strlen(str);   // ----
      for(int i=0;i<len;i++) // these lines are useless, you can print the string back with just "cout << str;"
        cout<<str[i];        // ----
      cout<<"\nContinue?\n";
      //cin>>ch;
      cin.getline(str,80);
   }
    while(str[0]=='y' || str[0]=='Y');
Edited by mike_2000_17 because: n/a
Member Avatar for anuj_sharma

Thanks a lot Mike. I got the solution and also learned somehting new.

:)

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