Chapter 2: Exercices program

[jerome]

CU Jerome

[mdeh]

Jerome,
Just post your code in plain, with the appropriate tags. I think people are a little reluctant to download zipped files from unknown sources...although I am sure yours would be fine.

[jerome]

Hi mdeh,

My feeling is that it's awfully painfull to have the source code in the post as it makes it a bit messy (where is the code and where are the comment). Of course nobody is obliged to trust me and download the file.

How much people just give their password to a program installer and don't know what's happen in it? I can live with the idea that the previouly mentionned people feel safer when retyping by hand the examples.

CU Jerome

[mdeh]

Hi mdeh,

My feeling is that it's awfully painfull to have the source code in the post as it makes it a bit messy

Code: (Objective-C)

(where is the code

and

where are the comment)  // or /*......*/

.

It's quite easy once you get the hang of it. But, as you say, everyone is different.

[Kari]

Personally I prefer to read the code within the body of a message.  I am not inclined to download code in a zipped file from anyone other than the author of the book.  Exercise 1 is as follows:

Program 2.1--

Code: (Objective-C)

//First program example

#import <Foundation/Foundation.h>

int main (int argc, constr char * argv[])

{
     NSAutoreleasePool * pool = [[NSAutorelease Pool alloc] init];
     NSLog (@"Programming is fun!";
     
     [pool drain];
     return 0;
}

Program 2.2--

Code: (Objective-C)

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[])

{
     NSAutoreleasePool * pool [[NSAutoreleasePool alloc] init];

     NSLog (@"Programming is fun!");
     NSLog (@"Programming in Objective-C is even more fun!");

     [pool drain];
     return 0;
}

Program 2.3--

Code: (Objective-C)

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[])
{
     NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
     
     NSLog (@"Testing... \n..1\n...2\n....3");
     [pool drain];
     return 0;

Program 2.4--

Code: (Objective-C)

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[])
{
     NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

     int sum;
     
     sum = 50 + 25;
     NSLog (@"The sum of 50 and 25 is %i", sum);
     [pool drain];
     
     return 0;
}

Program 2.5--

Code: (Objective-C)

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[])
{
     NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
     int value1, value2, sum;
     
     value 1 = 50;
     value 2 = 25;
     sum = value1 + value2;

     NSLog (@"The sum of %i and %i is %1", value1, value2, sum);
     
     [pool drain];
     return 0;
}

The exercise asks that we compare the output produced by each program.  Maybe later I will edit this post to include the output.

[Kari]

Chapter 2, Exercise 2 (page 25):

Code: (Objective-C)

#import <Foundation/Foundation.h>

int main (int argc, const char *argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    NSLog (@"In Objective-C, lowercase letters are significant.\n main is where program execution
    begins.\n Open and closed braces enclose program statements in a routine.\n
    All program statements must be terminated by a semicolon.");
    [pool drain];
    return 0;
}

[jkiley]

Chapter 2, Exercise 4 (p. 26)

Code: (Objective-C)

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    // Subtracts 15 from 87 and displays the output.
	
	int sum;
	
	sum = 87 - 15;
	
    NSLog(@"The difference between 87 and 15 is %i.", sum);
    [pool drain];
    return 0;
}

[jkiley]

Chapter 2, Exercise 5 (p. 26)

Code: (Objective-C)

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    // Corrects Chapter 2 Exercise 5 as instructed.
	
	int sum;
	
	// Compute result
	
	sum = 25 + 37 - 19;
	
	// Display results.
	
    NSLog(@"The answer is %i", sum);
    [pool drain];
    return 0;
}

[Intyre3]

Programming in Objective-C 2.0

Chapter 2. Exercises

 See prog1, Program 2.3, Program 2.4, and Program 2.5 at Desktop/Obective-C Projects.
 See C2E2 at Desktop/Objective-C Projects.
 Testing...
     ....1
     ...2
     ..3
See C2E4 at Desktop/Objective-C Projects
See C2E5 at Desktop/Objective-C Projects
    INT should be int
    sum = 25 + 37 - 19   should be   sum = 25 + 37 - 19;
    NSLog(@’ The answer is %i’ sum);   should be   NSLog(@”The answer is %i” , sum);
95

NOTE: Exercises 1, 2, 4 and 5 are the typed programs on my computer.  They are not included in these answers.

[mylifeis24]

Hello,

I am just starting the book and so far I am doing fine, but when I type my code in for exercise 2.5, I always get an error that says...

error: syntax error before 'value2'

Below is the whole code with the error, but it is the same as the one in Program 2.5 on pg. 24.

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
   
   int value1, value2, sum;
   value1 = 50
   value2 = 25
//This is where the error appears
   sum = value1 + value2;
   NSLog(@"The sum of %i and %i is %i", value1, value2, sum);
   
   [pool drain];
   return 0;
}

Thank you for any help you may provide.

[EnzoBro]

@ mylifeis24

you forgot to put the semicolon at the end of your statements

value1 = 50;
value2 = 25;

[mylifeis24]

@ mylifeis24

you forgot to put the semicolon at the end of your statements

value1 = 50;
value2 = 25;

Wow.... I spent a good 10 minutes looking over that short piece of code and missed that! Even for someone new to this that is a little frightening. Thanks a lot.

[EnzoBro]

You are not alone, I spent 20 minutes in the Book and Xcode and another 20 minutes in these forums looking for an error in Program 3.2.
Only to find out i typed:
myfunction
instead of
myFunction

I am new like you and we will get through this. One error at a time.

[skochan]

This is a valuable part of the learning process, which I why I discourage new programmers from just copying and pasting the program examples into Xcode.

Cheers,

Steve

[mylifeis24]

This is a valuable part of the learning process, which I why I discourage new programmers from just copying and pasting the program examples into Xcode.

Cheers,

Steve

I try and read the description before I enter the code, so that as I enter it, I can understand what it is I am typing!

Its a great book, great tool for beginners and this site is most certainly extremely helpful to anyone with questions or an idea.