[Tutorial] Introduction to programming using C (VIII)

[m0skit0]

Ok, here go my comments:

Spoiler

Code: Select all

#define size 10

Constants go all caps. E.g. SIZE. Not written anywhere; it's a convention.

Code: Select all

c += 1;

And why not c++ Also use a more descriptive name for this variable.

I didn't understand this: "2 first multiple of 3 numbers."

I express myself like an arse. I meant the 2 first numbers that are multiple of 3.

[Wdingdong]

And why not c++

Hehe, So stupid of me May be due to rote learning system in my country

Okay,

Ascending sorting

Code: Select all

#include<stdio.h>
#define SIZE 10

int main()
{
   int a [SIZE] = { 4, 6, 7, 3 ,2, 1, 0, 9, 5, 8};
   int i, j, temp;
   for(i = 0; i < SIZE; i++)
   {
      for(j = 0; j < (SIZE - 1); j++)
      {
         if(a[j] > a[j+1])
         {
            temp = a[j];
            a[j] = a[j+1];
            a[j+1] = temp;
         }
      }
   }
   printf("Array after sorting: \n");
   for(i = 0; i < SIZE; i++)
   {
      printf("%d\n", a[i]);
   }
   return 0;
}


Check Equal Strings(Case Sensitive)

Code: Select all

#include<stdio.h>
#define SIZE 10

int main()
{
   char s1[SIZE] = "equal";
   char s2[SIZE] = "Equal";
   int i;
   int count = 0;            //Counter to count unequal characters
   for(i = 0; s1[i] != '\0' || s2[i] != '\0'; i++)
   {
      if(s1[i] != s2[i])
      {
         count++;
      }
   }
   if(count == 0)
      printf("Strings are equal");
   else
      printf("Strings are not equal");
   return 0;
}


Check Equal Strings(Not Case Sensitive)

Code: Select all

#include<stdio.h>
#define SIZE 10

int main()
{
   char s1[SIZE] = "equalL";
   char s2[SIZE] = "Equall";
   int i;
   int count = 0;            //Counter to count unequal characters
   for(i = 0; s1[i] != '\0' || s2[i] != '\0'; i++)
   {
      if(s1[i] != s2[i])
      {
         if(s1[i] > s2[i] && s1[i] - 32 != s2[i])      //The difference between value of upper and lower case is 32
            count++;
         else if(s2[i] > s1[i] && s2[i] -  32 != s1[i])
            count++;
      }
   }
   if(count == 0)
      printf("Strings are equal");
   else
      printf("Strings are not equal");
   return 0;
}


Three First Multiple of 3

Code: Select all

#include<stdio.h>
#define SIZE 10

int main()
{
   int i, j = 0;
   int a[SIZE] = {1, 3, 5, 6, 9, 12, 15, 9, 6, 9};
   for(i = 0; i < SIZE; i++)
   {
      if(a[i] % 3 == 0 && j < 3)
      {
         printf("%d\n",a[i]);
         j++;
      }
   }
   return 0;
}


Matrix Addition

Code: Select all

#include<stdio.h>

int main()
{
   float a[3][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
   float b[3][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
   float c[3][3];
   int i, j;
   printf("Matrix Addition:\n");
   for(i = 0; i < 3; i++)
   {
      for(j = 0; j < 3; j++)
      {
         c[i][j] = a[i][j] + b[i][j];
         printf("%f\t", c[i][j]);
      }
      printf("\n");
   }
   return 0;
}


I'm stuck with checking the substring. It'd be good if you help a little

[m0skit0]

Sorry for the lateness

Ascending sorting

Ok

Check Equal Strings(Case Sensitive)

Why you keep comparing characters when you already know they are not equal? Waste of processing time.

Check Equal Strings(Not Case Sensitive)

Same as previous one and also:

Code: Select all

         if(s1[i] > s2[i] && s1[i] - 32 != s2[i])      //The difference between value of upper and lower case is 32
            count++;
         else if(s2[i] > s1[i] && s2[i] -  32 != s1[i])
            count++;

Always use {}. You'll save yourself headaches later. Also don't you think this kind of cumbersome? Can you see a better way to do this instead of having those ifs and -32 repeated?

Three First Multiple of 3

There's no such exercise... You probably meant the 2 first multiples of 3. Anyway, you keep reading the array even if you don't need to (same error as 2 previous exercises).

Matrix Addition

Ok

I'm stuck with checking the substring. It'd be good if you help a little

What's the problem?

[0xB16B00B5]

[*]Write a program that given an array of 10 numbers, prints only the even numbers.

Spoiler

Code: Select all

#include <stdio.h>

#define ARRAY_SIZE 10

main()
{
   int array[ARRAY_SIZE] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
   int a;

   for (a = 0; a <= 9; a++)
   {
      if (array[a] % 2 == 0)
      printf("%d\n", array[a]);
   }
} 

[*]Write a program that given an array of 10 numbers, prints only the odd positions.

Spoiler

Code: Select all

#include <stdio.h>

#define ARRAY_SIZE 10

main()
{
   int array[ARRAY_SIZE] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
   int a;

   for (a = 0; a <= 9; a++)
   {
      if (array[a] % 2 == 1)
      printf("[%d] ", a+1);
   }
   printf("\n");
} 

Doesn't actually print the position in the array. Oh, and if the "a+1" looks weird, I'm just expirementing with stuff.
The output gives me even numbers, so a+1 makes them odd.
I don't know (I have a horrible memory so sorry if you've already covered that) how to actually print the position from the array.

[*]Write a program that given an array of 10 numbers, prints only the 2 first multiple of 3 numbers.

Spoiler

Code: Select all

#include <stdio.h>

#define ARRAY_SIZE 10

main()
{
   int array[ARRAY_SIZE] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
   int a, b;

   a = 0;
   b = 0;

   while (b < 2)
   {
      if (array[a] % 3 == 0)
      {
      printf("%d\n", array[a]);
      b++;
      }
   a++;
   }
}

Tried getting a bit creative for this one.

[*]Write a program that given one string, prints its length.

Spoiler

Code: Select all

#include <stdio.h>

#define ARRAY_SIZE 10

main()
{
   int a;

   while (getchar() != EOF)
   a++;

   printf("%d", a);
}

Not sure if that's what you wanted.. correct me if I'm wrong.

I'll do the others later.

[m0skit0]

Cool. I spoiled your answers so you don't spoil stuff to people trying to do the exercises themselves

And some comments:

Look to format better your code. Check my code on how to use indentation correctly.

Code: Select all

main()

Wrong main() declaration. main() must return int in standard C.

Code: Select all

      if (array[a] % 2 == 0)
      printf("%d\n", array[a]);

Never use ifs without braces. You'll avoid headaches in the future.

Code: Select all

for (a = 0; a <= 9; a++)

You're using a literal here. You actually don't need to. That's why you have ARRAY_SIZE.

Write a program that given an array of 10 numbers, prints only the odd positions.

You understood bad the goal of this exercise. You have to print the values of the array that are in odd positions, taking position in the array like 1st element (odd) is index 0, 2nd element (even) is index 1, and so on.

Oh, and if the "a+1" looks weird, I'm just expirementing with stuff.

It does not. I'm a programmer, dude

I don't know (I have a horrible memory so sorry if you've already covered that) how to actually print the position from the array.

You do it in the first exercise

Tried getting a bit creative for this one.

I don't see that much creativity, but only the best way to do it. Congrats!

Not sure if that's what you wanted.. correct me if I'm wrong.

Not really, although your code is OK. Take this skeleton and try to complete it to do what's asked:

Code: Select all

#include <stdio.h>

int main()
{
   char* target = "This is the string you have to calculate its length";
   int length = 0;
   
   // Put your code here!
   
   print("The length of the target string is %d\n", length);
   
   return 0;
}

Code: Select all

   while (getchar() != EOF)
   a++;

Same as with ifs: never use while without braces. This is friend's advice!

[PrimeNexes]

I know the C and some C++ I wanted to know what more is required to write for PSP ?

[m0skit0]

Nothing more if you can read documentation and know how to install the tools.

Also just FYI: I've heard a lot of people saying they already know C/C++ and couldn't understand PSPSDK documentation... This simply means you don't know C/C++. Knowing C/C++ is not knowing how to write a "Hello World" for Windows. It's knowing how C/C++ works. C/C++ works the same no matter the platform. Only system calls change from one platform to another.

[Wdingdong]

Why you keep comparing characters when you already know they are not equal? Waste of processing time.

Is this okay?

CHECK EQUAL STRINGS(Case sensitive)

Code: Select all

#include<stdio.h>
#define SIZE 10

int main()
{
   char s1[SIZE] = "equal";
   char s2[SIZE] = "equal";
   int i = 0;               //Used as counter and loop variable
   while(s1[i] == s2[i])
   {
      i++;
   }
   if(i == SIZE)
   {
      printf("The strings are equal");
   }
   else
   {
      printf("The strings are not equal");
   }
   return 0;
}


[PrimeNexes]

Thanks for your reply m0skit0 .I will try my best .

[m0skit0]

Is this okay?

No, it's not. It's worse than before because this has several bugs:

• Potentially infinite loop
• Could say false when 2 strings are equal if at least one byte after the NUL character is equal

Your problem here is that you continue comparing past the end of string.