A rewrite for http://www.reddit.com/r/readablecode/comments/1ax50c/looking_for_style_critique_new_c_user/

rewrite

#include <iostream>
#include <iomanip>
#include <cstdlib>

// Prototypes
void printHead();
void calcPieces();

float loanAmt = 0;  // Total loan amount
double intRate = 0; // Interest rate as xx.xxx%
float pAmt = 0;     // Payment amount
int pNum = 1;       // Payment number counter
float tPrincipal;   // Total principal
float tInterest;    // Total interest
double principal;   // Current principal
double interest;    // Current interest
float balance;      // Present value of loan

int main() {
    // Collect information
    while (loanAmt <= 0) {
        std::cout << "Please input loan amount: ";
        std::cin >> loanAmt;
        if (loanAmt <= 0) {
            std::cout << "Invalid amount entered, please enter another one: ";
        }
    }
    while (intRate <= 0) {
         std::cout << "Please input interest rate as xx.xxx%: ";
         std::cin >> intRate;
         if (intRate <= 0) {
             std::cout << "Invalid amount entered, please enter another one: ";
         }
         intRate /= 100;
    }
    while (pAmt <= 0) {
        std::cout << "Please input monthly payment amount: ";
        std::cin >> pAmt;
        if (pAmt <= 0) {
            std::cout << "Invalid amount entered, please enter another one: ";
        }
    }
    balance = loanAmt;
    interest = 0.0;
    
    // This needs to be the error check
    
    while (balance > 0.0) {
        printHead();
        while(pAmt <= balance) {
            calcPieces();
            if (pNum % 20 == 1) {
                system("pause");
                printHead();
            }
        }
        calcPieces();
        balance = 0;
        system("pause");
    }
    
    return 0;
}

void printHead() {
    std::cout << "PAMT #   PAMT AMT   PRINCIPAL      INTEREST        BALANCE   TTL INT  TTL PRIN" << std::endl;
    std::cout << "==============================================================================" << std::endl;
}

void calcPieces() {
    // Calc interest and principal, add to the totals, also balance
    interest = balance * (intRate/12);
    principal = pAmt - interest;
    tInterest += interest;
    tPrincipal += principal;
    balance -= pAmt - interest;

    std::cout << setprecision(2) << std::fixed;
    std::cout << std::right;
    std::cout << std::setw(5);
    std::cout << pNum;
    std::cout << std::right;
    std::cout << setw(9);
    std::cout << pAmt;
    std::cout << std::right;
    std::cout << setw(14);
    std::cout << principal;
    std::cout << std::right;
    std::cout << setw(14);
    std::cout << interest;
    std::cout << std::right;
    std::cout << setw(14);
    std::cout << balance;
    std::cout << std::right;
    std::cout << setw(10);
    std::cout << tInterest;
    std::cout << std::right;
    std::cout << setw(14);
    std::cout << tPrincipal << std::endl;         

    pNum++;
}