On the internet I found the code below. The code does what it is supposed to do: solving quadratic equations. My question is: if you were to rate this code on a scale from 1 (terrible, couldn't be worse) to 10 (expert, couldn't be better), knowing that the programmer makes a living out of programming. All indentation and comments is his/hers.

Thanks you for you time, Bilderbikkel

[code]

#include

#include

#include

using namespace std;

void one(){

float a = 0.0; //here we declare the variables and use float because we

float b = 0.0; //are dealing with square roots

float c = 0.0;

float x1 = 0.0;

float x2 = 0.0;

float x3 = 0.0;

float x4 = 0.0;

//this section gets user input and displays message

cout << "Enter the coefficients a , b , c for equation in the form ax^ + bx + c = 0:

";

cout << "Enter value for a:

";

cin >> a;

cout << "Enter value for b:

";

cin >> b;

cout << "Enter value for c:

";

cin >> c;

//are all the coefficients 0? if so both roots are 0

if(a == 0 && b == 0 && c == 0){

x1 = 0;

x2 = 0;

cout << "The roots are:" "

"

<< "x1 = " << x1 << " , " << "x2 = " << x2 << "

";

}

//is c the only non-zero number? if so tell the user

if(a == 0 && b == 0 && c != 0){

c = c;

cout << "There are no roots" "

"

<< "c = " << c << "

";

}

//is a zero? if so solve the resulting linear equasion and notify user

if(a == 0 && b != 0 && c !=0){

cout << "The values entered do not make a quadratic expression" "

"

<< "x = " << -c/b << "

";

}

//if b is zero and c is zero tell user

if(a == 0 && b != 0 && c == 0){

x1 = 0;

x2 = 0;

cout << "The roots are:" "

"

<< "x1 = " << x1 << " , " << "x2 = " << x2 << "

";

}

//if b and c are equal to zero then ax^=0 and since a cannot be zero without x being

// zero also let user know

if(a != 0 && b == 0 && c == 0){

x1 = 0;

x2 = 0;

cout << "The values entered result in ax^= 0; so both roots are 0" "

"

<< "x1 = " << x1 << " , " << "x2 = " << x2 << "

";

}

//factor out x from ax^+bx=0 and either x = 0 or ax + b =0

//then solve the linear equation

if(a != 0 && b != 0 && c == 0){

x1 = 0;

x2 = -b/a;

cout << "The roots are:" "

"

<< "x1 = " << x1 << " , " << "x2 = " << x2 << "

";

}

//now we get to use the square root function and let the user

//know they have some imaginary numbers to deal with

if(a < 0 && b == 0 && c < 0){

x1 = -b/(2*a);

x4 = (b*b)-(4*a*c);

x4 = -x4;

x2 = sqrt(x4)/(2*a);

x3 = -sqrt(x4)/(2*a);

cout << "The roots are not real numbers:" "

"

<< "x1 =" << x1 << " + " << x2 << " * i " << "

"

<< "x2 =" << x1 << " + " << x3 << " * i " << "

";

}

if(a > 0 && b == 0 && c > 0){

x1 = -b/(2*a);

x4 = (b*b)-(4*a*c);

x4 = -x4;

x2 = sqrt(x4)/(2*a);

x3 = -sqrt(x4)/(2*a);

cout << "The roots are not real numbers:" "

"

<< "x1 =" << x1 << " + " << x2 << " * i " << "

"

<< "x2 =" << x1 << " + " << x3 << " * i " << "

";

}

//now a and c are opposite signs so the answer will be real

if(a > 0 && b == 0 && c < 0){

x1 = (-b + (sqrt(pow(b,2)-(4*a*c))))/(2*a);

x2 = (-b - (sqrt(pow(b,2)-(4*a*c))))/(2*a);

cout << "The roots are:" "

"

<< "x1 = "<< x1 << " , " << "x2 = "<< x2 << "

";

}

if(a < 0 && b == 0 && c > 0){

x1 = (-b + (sqrt(pow(b,2)-(4*a*c))))/(2*a);

x2 = (-b - (sqrt(pow(b,2)-(4*a*c))))/(2*a);

cout << "The roots are:" "

"

<< "x1 = "<< x1 << " , " << "x2 = "<< x2 << "

";

}

//ok now if we end up not having to take the square root of a neg

// do the math

if(a != 0 && b != 0 && c != 0 && (4*a*c) <= pow(b,2)){

x1 = (-b + (sqrt(pow(b,2)-(4*a*c))))/(2*a);

x2 = (-b - (sqrt(pow(b,2)-(4*a*c))))/(2*a);

cout << "The roots are:" "

"

<< "x1 = "<< x1 << " , " << "x2 = " << x2 << "

";

}

//here we have to deal with non x intercepts ie: sqrt(-1)

// alter the formula slightly to give correct output and

// let the user know

if(a != 0 && b != 0 && c != 0 && (4*a*c)> pow(b,2)){

x1 = -b/(2*a);

x4 = (b*b)-(4*a*c);

x4 = -x4;

x2 = sqrt(x4)/(2*a);

x3 = -sqrt(x4)/(2*a);

cout << "The roots are not real numbers" "

"

<< "x1 =" << x1 << " + " << x2 << " * i " << "

"

<< "x2 =" << x1 << " + " << x3 << " * i " << "

";

}

char g;

cout << "Solve another equation? (y for yes or n for no)

";

cin >> g;

if(g !='y'){

exit(0);

}

return;

}

//keep output from vanishing before we can read it.

void two(){

char g ;

cout << "Press c and then Enter to continue...." "

";

cout << "Press s and then enter to stop....." "

";

cin >> g;

if (g == 'c')

for(int i=0; i<100; i++)// who wants to run this more that 99 times? if you are using this program for

//any thing other than some quick calculations (for example as part of another program)

// you may want to comment this part out. The for loop keeps the program from

//running away in an infinate loop, but may not be usable in another program.

//If 99 times is not enough, change the value in the for loop, but be careful

//with no limits the for loop can run the program in the background by accident

one();

}

int main(){

one();

two();

return 0;

}

[/code]

bilderbikkel

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## Comments

Main issues are:

- Poor indention. It isn't readable.

- Lack of modular programming. It should have functions or a class for the calculations, and those functions shouldn't contain user i/o.

- Obfuscation. Lines like

x1 = (-b + (sqrt(pow(b,2)-(4*a*c))))/(2*a);

aren't readable.

- The code doesn't handle the line feed character from stdin.

- Implicit typecasts between int and float. This is a potential bug, as one doesn't know if "int" is signed or unsigned when dealing with portable code.

Minor issues:

- Implicit typecasts between float and double. Creates unnecessary execution time and program size.

- No function prototypes.

- math.h instead of

- The code is using the questionable exit() function.