Convert string to number and vice versa

When you are writing a computer program, you might want to convert a string to number or vice versa. This might be a problem for C++ beginners. This tip helps you to solve this problem.

In C++, you can use the atoi, atol, atof, and strtod functions to convert a string to integer, long, float, and double numbers respectively. In contrast, you will use the str() method of the ostringstream class to convert a number to string. The ostringstream class is in the sstream header file. You need to include this header file by adding the line: #include<sstream> to the header section of your program.

In the example program keeps data of a number of students. Each student contains id, name, final score, and mid-term score. These data are string values that will be input by user. A two-dimensional array is used to store the data. After the data are input, the program will display the data in a table. This table also includes the total scores of each student. A total score is calculated by adding the final and mid-time scores together.

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

void st(int n){
  
   int c=5;
   string ar[n][c];
   char con='y';
   int i=0;
   while((con!='n') && (i<n)){
           cout<<"id:";
           cin>>ar[i][0];
           cout<<"name:";
           cin>>ar[i][1];
           cout<<"final score:";
           cin>>ar[i][2];
           cout<<"mid score:";
           cin>>ar[i][3];
           i++;          
           cout<<"Press y to continue or n to stop:";
           cin>>con;
          
            }
       int j=0;
       while(j<i){
               ostringstream oss;
               oss<<strtod(ar[j][2].c_str(),NULL)+strtod(ar[j][3].c_str(),NULL);
               ar[j][4]=oss.str();
      
               j++;
       }
    
       for(int r=0;r<i;r++)
             {
             for(int c=0;c<5;c++)
                  cout<<ar[r][c]<<"\t";
             cout<<"\n";
              }    

    
  
   }
int main()
{

st(2); //two students for an example
      
system("PAUSE");
return 0;
}

Convert-string-to-number-and-vice-versa

Posted by: Dara | post date: 12-31-2013 | Subject: C++ Programming Language

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