How to show numbers in cout without the "e" notation? - c++

Question

I tried to print a 'power table' of numbers without having them displayed using the "e" format but I can't figure out what's wrong. Here's my program:
#include <iostream>
#include <cmath>
using namespace std;
int main() {
double num [11][11];
for (int i=0; i<=10; i++)
{
cout << "\t^" << i;
}
cout << endl;
for (int row=1; row<=10; row++)
{
cout << row << "\t";
for (int col=0; col<=10; col++)
{
num [row][col] = pow (row,col);
cout << num [row][col] << "\t";
}
cout << endl;
}
return 0;
}

Answer 1

You can use the setiosflags function with std::ios_base::fixed as its argument to specify that scientific notation (using the 'e') should not be used; you will also (most likely) need to call setprecision with an argument of 0.
Add this line near the start of your main function:
std::cout << std::setiosflags(std::ios_base::fixed) << std::setprecision(0);
Be sure to also add #include <iomanip> to your code. Also note that, using such (fixed) output format will mess up your table when there are more digits in the number than the width of the tab stops (typically 8 characters). Handling such cases is a slightly different issue, though. One way would be to add two tabs for each column, only printing the second for the first column or if the value in the previous column has less than 8 digits; something like this (assuming 8 chars per tab-stop):
#include <iostream>
#include <cmath>
#include <iomanip>
int main()
{
std::cout << std::setiosflags(std::ios_base::fixed) << std::setprecision(0);
double num[11][11];
for (int i = 0; i <= 10; i++) {
std::cout << "\t\t^" << i; // Two tabs per column
}
std::cout << std::endl;
for (int row = 1; row <= 10; row++)
{
std::cout << row << "\t";
for (int col = 0; col <= 10; col++)
{
num[row][col] = pow(row, col);
if ((col == 0) || (num[row][col-1] <= 9999999)) std::cout << "\t"; // Need the extra tab
std::cout << num[row][col] << "\t";
}
std::cout << std::endl;
}
return 0;
}