Written By:X_console
shellscope@yahoo.com
Continued...

Was there a better way of writing this? You bet. Use the "switch" case statement instead. Switch is neat:

switch(a)
{
        case 0: a++; 
                return(a);

        case 1: a += 5;
                return(a);

        case 2: a += 10;
                return(a);

        case 3: a += 20;
                return(a);

        default: exit(1);
}

Here we see the various cases and what they do depending on the value of "a". When a no-match is found, it automatically goes to the default action, which in this case is to exit.

Abusing Nesting

Obviously this is exaggerating a little, but you'd be surprised how some people actually do this. So how do we fix it? One way, is perhaps to break it up with functions:

void next(int a, int b, int c, int d)
{
if(c != b)
{
        c = c + 1;
        if(d > (a + b))
        printf("Made it all the way to the bottom!\n");
        }
}       

int main()
{
        int a = 10; 
        int b = 20; 
        int c = 30; 
        int d = 40;

        if(a == 10)
        {
                a = a + d;
                if(b == 20)
                {
                        b = b + a;
                        next(a, b, c, d);
                }
        }
        return(0);
}

Okay, this took a bit more work, but now your code is structured and easier to read. Sometimes it takes a little bit more code in order to make the overall code easier to understand. Don't be lazy.

Commenting Code

int x = 100;
int y = 1000;

if(x < y)
        a = 0;
else
        a = 1;

Can you tell what this program does? What it's purpose is? No. Not without knowing what the variables x, y, and a represent. Now let's comment it: /*
* a program that checks for profit and loss:
*/
int x = 100;
/* x is the total amount of money gained from selling books */
int y = 1000
/* y is the cost spent to manufacture the books */
int a;
/* determines whether we made a profit or loss */
/* check to see if x is less than y: */
if(x < y)
/* we made a loss. let the number 1 stand for loss:
a = 1;
else
/* we made a profit. let the number 0 stand for profit */
a = 0;

Now even if you don't program in C, you already know what this program does. You have an idea of what each statement does, and you know what each variable stands for. I said that commenting is good. But over commenting your code is bad. You use comments to make certain code easier to understand, but you don't use comments to tell a story:

int profit = 1; /* profit is equal to 1 */
int loss = 0;   /* loss is equal to 0 */

/* if profit equals to 1: */
if(profit == 1)
        /* print "We made a profit!" */
        printf("We made a profit!\n");

/* else: */
else
        /* print "We made a loss!" */
        printlf("We made a loss!\n");

This is an amazing waste of time. You're telling the programmer the obvious. Commenting is best used when you're declaring variables, and when you're performing some operation on variables. You need to tell the programmer what each variable represents, and what happens to each variable. You need to tell the programmer what your program does, and how it does what it does. You need to tell the programmer what each function, method, procedure, and error code does. The programmer does not want to guess.

Naming

void x(int a, int b)
{
        int z;
        z = a + b;
        printf("z is %d\n", z);
}

Here we have an idea of what procedure x does, but we don't know what it represents. We also do not know what a, b, and z represent. Let's modify it a litte:

void sum_of_ages(int jacks_age, int jills_age)
{
        int total_age;
        total_age = jacks_age + jills_age;
        print("total_age is %d\n", total_age);
}

Now here, the code is uncommented, but because of the way you've named the variables, anyone who looks at your code, can get a general idea of what you're trying to do here. We know what each variable represents and we know for sure what the function's supposed to do. A program with well named functions and variables might not need a lot of commenting.

Checking The Buffer

char city[10];

/* array that holds the name of a city */

printf("Enter a city name: ");
scanf("%s", city);
printf("City is %s\n", city);

Now this assumes that the city name is 9 elements long (the 10th element is the terminating null character: \0). So what happens when the user enters a name longer than 9 characters? Nothing might happen, or the program might crash, or overwrite data beyond the buffer. Either way, don't risk it. Check the input length:

char city[10];

/* array that holds the name of a city */

printf("Enter a city name: ");
fgets(city, sizeof(city), stdin);

printf("City is %s\n", city);

What happens here is that if the user enters more than what the buffer can hold, the extra input is truncated off.

Never Trust The User

Conclusion

X_console
shellscope@yahoo.com