C++ program instruction

I have written this program, however when I try to compile it I get a syntax errors. I cannot find where the syntax errors are.

It should calculate number of second sound travels in difference gases, information given by user.

include <iostream>
#include <fstream>
using namespace std;

   int main()
         {
          int choice, gascount=0,i,sec;
          string gas[10],type;
          double speed[10],speedd;
          ifstream input;
   input.open("input.txt"); 
   if(input.fail())            
          cout<<"file did not open please check it\n";
          cin >> gas[gascount++];
      while(input)
          {
              input>>speed[gascount];
              input>>gas[++gascount];
          }
           while(choice!=5)  
               {cout<<"Choose gas would you like to use\n";
                cout<<"1  CarbonDioxide\n";
                cout<<"2  Air\n";
                cout<<"3  Helium\n";
                cout<<"4  Hydrogen\n";
                cout<<"5  Exit\n";  //5th cout for exiting program
                cin >>choice;

     switch(choice)    //use swich for user selection of gases 
        {case 1:    type="CarbonDioxide";
                    break;
         case 2:    type="Air";
                    break;
         case 3:    type="Helium";
                    break;
         case 4:    type="Hydrogen";
                    break;
         case 5:    system("exit");
         default:   printf("Illegal input: Try Again\n");
         }
          i=0;
          for(i=0;i<gascount;i++)            //loop for number of seconds
             if(type.compare(gas[i])==0)   //speed travel in gases
                {speedd=speed[i];
                 i=gascount+1;
         开发者_开发百科        }
      cout<<"You chose "<<type<<endl;
      cout<<"how many seconds did the sound travel? ";
      cin>>sec;
      while(sec<0||sec>30)
         {cout<<"must me between 0 and 30\n";
          cout<<"how many seconds did the sound travel? ";
          cin>>sec;
         }
          cout<<"The speed of sound through "<<type<<" is "<<speedd*sec*10.<<endl;
    }
    input.close();
    system("pause");

 return 0;

}

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Your complier has error messages. You need to look at those messages and fix them one at a time If you can't figure one our repost it.

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I could see 2 problems:

In the first line # is missing before the include ( could be a typo)

You are using the system function but not including stdlib, you need a

#include <cstdlib>

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Once you've fixed the problems @codaddict pointed out, you probably also want to #include <string>, since you're using std::string.

Although it's not directly related, you should also work on indenting your code a bit more meaningfully.

It looks like you're also using choice before you initialize it.

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Yes, you are probably missing

#include <cstdlib> // system() defined here
#include <string>  // std::string here

• Don't miss to include required headers.
• Work on your indentation.
• There is no problem with choice but initializing it at the point of definition would be good style.

• Take into account warnings too

  prog.cpp:40: warning: ignoring return value of ‘int system(const char*)’, declared with attribute warn_unused_result

  prog.cpp:60: warning: ignoring return value of ‘int system(const char*)’, declared with attribute warn_unused_result

  prog.cpp:11: warning: ‘speedd’ may be used uninitialized in this function

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#include <stdlib> and #include <stdio> may help...

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Just add #include < string > and your program will compile perfectly :)