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| Re: Lets Learn C by stack1(m): 9:01am On Jul 30, 2016 |
lets see some basic examples
in the first example we declare a variable index and set its value to 1, then the control-expression index < 5 is evaluated, so far as this expression returns a positive/truthful result the loops body i.e. the printf statement is executed. in the second example the variables are the same the only difference is the control-expression --index < 5, this statement uses a pre-decrement to decrease the value of the variable index by one each time the loop is run, however this example prints a never ending line of Good morning's, this is termed infinite looping and is usually an error condition, before i explain while the loop runs infinitely can any one take a stab at the explanation  And also the second example shows a crucial point, whenever you craft loops, make sure there's some condition that would cause the loop to terminate and not just run endlessly, except you actually wanted it to (this could be valid ins some kind of programs) |
| Re: Lets Learn C by stack1(m): 9:06am On Jul 30, 2016 |
while and for loops are termed entry condition loops, this is due to the fact that their condition(s) for looping is checked each time before the loop is executed, the examples seen so far are quite basic, as we proceed we would encounter more complex (and sometime strange) usages of loops. so lets see some more while loops |
| Re: Lets Learn C by stack1(m): 9:55am On Jul 30, 2016 |
// Program to find factorial of a number // For a positive integer n, factorial = 1*2*3...n Ok, not too get too mathematical (no be say me sef sabi math like dat), but this example calculates factorial, in summary lets say we have a number 5 the factorial would simply be 1*2*3*4*5, and if w have a number 55 the factorial would be 1*2*3*4*5*....55, ok they are other better ways to calculate factorials and we would still revisit more proper factorial programs later on
This example calculates the factorial of 8, the loop's control-condition simply checks to make sure the value of the number variable is greater than 0 (initially its 8 ). In the body of the loop we calculate the factorial as thus on the first run factorial is 1 and number is 8 so factorial = factorial * number;, evaluates as 1 = 1* 8 which is still 8 and so the number 8 is stored in the factorial variable, i.e. factorial = 8 The next statement --number, decreases the value of number by one making it 7 On the next run of the loop the control-condition (number > 0) still holds true as number is 7 and thus > 0 so the loop is executed again and - factorial = factorial * number;, evaluates as 8 = 8* 7, given 56, and this is stored in factorial. The statement --number, decreases the value of number by one (again) making it 6. This process runs again and again updating the factorial variable and decreasing the number on each successfull run until the condition (number > 0) isn't true any more and the looping stops. The final value stored in variable factorial is our answer and is printed to the output |
| Re: Lets Learn C by stack1(m): 10:03am On Jul 30, 2016 |
The while and for loops as stated earlier are entry-controlled loops as their conditions for looping is checked once before each run, however there exists another similar looping construct do..while which runs at least once before its looping condition is checked and it is termed an exit-controlled loop [size=16pt]do while{}[/size] The do while{} loop executes its statement(s) once before checking its loop-condition, if the loop-condition then still holds true it executes again and again till the condition is no longer true Form of do-while loop –
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| Re: Lets Learn C by stack1(m): 10:15am On Jul 30, 2016 |
Ok so what is happening here, we have an integer variable j that is initialized to zero, in the do while loop, the statement which prints the value of our integer variable is printed first (in the do section), then the variable is incremented. all this happens before the looping condition j <= 8is checked This loop continues to run (increasing the value of the integer variable j on each run till the test-condition fails, that's basically the story of the do-while loop |
| Re: Lets Learn C by stack1(m): 10:20am On Jul 30, 2016 |
//carefully study the following code, would discuss it a bit later, its nothing complex just a lumped up example of what we have been looking at
Please make sure you type and run this code, and yeah i'm sure they'll be questions and some attacks for this   |
| Re: Lets Learn C by stack1(m): 1:29am On Aug 01, 2016 |
very tired tonight so i'll just run down a few C operators and their usage, most would be understood from their mathematical usage anyway, then gain forgive me I'm so stressed up right now, lemme leave you with this page that rounds up the C operators pretty well http://www.tutorialspoint.com/cprogramming/c_operators.htm Their usage would still be explained further in examples to come.. ..Serious sleep-mode things  |
| Re: Lets Learn C by stack1(m): 1:32am On Aug 01, 2016 |
and also make una ask questions oo.. |
| Re: Lets Learn C by romme2u: 6:08am On Aug 02, 2016 |
stack1: hey bro nice job my problems are in union, bit manipulations and dynamic structures. maybe when u get there we will tangle. |
| Re: Lets Learn C by stack1(m): 7:46am On Aug 02, 2016 |
thanks @romme2u, no p, looking forward to tangle |
| Re: Lets Learn C by shobam1410(m): 7:38am On Aug 03, 2016 |
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| Re: Lets Learn C by stack1(m): 9:49am On Aug 03, 2016 |
shobam1410: while i must agree this is really a nice collection of books (i actually have a few of them) this thread isn't for advertisements, if you are going to post please post on relevant topics being discussed, thank you |
| Re: Lets Learn C by stack1(m): 12:10pm On Aug 03, 2016 |
The C language includes a wide variety of powerful and flexible control statements, we have already seen the "loop-control" statements, now we look at the decision making statements. The most useful of these are described in the following. The if-else statement is used to carry out a logical test and then take one of two possible actions, depending on whether the outcome of the test is true or false. The else portion of the statement is optional. Thus, the simplest possible if-else statement takes the form:: if (expression) statement The expression must be placed in parenthesis, as shown. In this form, the statement will only be executed if the expression has a nonzero value i.e if expression if true, If the expression has a value of zero / if expression is false) then the statement will be ignored. The statement can be either simple or compound.
An else statement matches the nearest previous if statement in the same scope or block: The else in this code:
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| Re: Lets Learn C by stack1(m): 12:42pm On Aug 03, 2016 |
The ternary operator ( ?: ) is another powerful and useful conditional expression used in C and C++. It's effects are similar to the if statement but with some major advantages. The basic syntax of using the ternary operator is thus: (condition) ? (if_true ) : (if_false ) which is basically the same as
Therefore if "condition" is true, the second expression is executed ("if_true" ), if not, the third is executed ("if_false" ). as an example, assuming we have two int variables, and we wanted to compare them
This could be re-written as
A notable difference here is that the result of a Tenary expression can be stored or assigned to a variable, while an if-else statement doesn't return a result, though the assignment can be done within its execution block/scope |
| Re: Lets Learn C by stack1(m): 2:01pm On Aug 07, 2016 |
Lets look at some more Loop/Control structures examples The program below simply counts the number of lines in an input
Here's how the program works 1. In the main function we declare two int variables c and nl 2.In the while loop we read in characters into variable c until we detect the END_OF_FILE character 3. now in the body of the while loop we check for the newline character \n and whenever it is detected it means the user entered text on a new line so we increment the nl variable ( variable nl here is our number-of-lines counter) When entering input for this program enter as many number of lines of text as you wish then press Crtl+Z, this would send the EOF character to your program and the loop would exit The next line containing the function printf, prints out the value of the[b] nl[/b] variable, which shows the number of lines in our input |
| Re: Lets Learn C by stack1(m): 6:07pm On Aug 08, 2016 |
nawa o, i was trying to post afew more tutorials yesterday when i got banned by the antispam bot for a full 24hrs, biko antispam bot wetin i do u |
| Re: Lets Learn C by Nobody: 6:32pm On Aug 08, 2016 |
That was what frustrated many people including me from posting tutorials on nairaland. I think the special characters we use in programming and hyperlinks somehow trigger this automatic ban. |
| Re: Lets Learn C by stack1(m): 7:03pm On Aug 08, 2016 |
dhtml18: toh, taught as much, hope it doesn't occur frequently, don't know how much more of such frustrations i can take, but by the way sef i usually put program text between d code tag.., it is well sha |
| Re: Lets Learn C by stack1(m): 11:12pm On Aug 08, 2016 |
This next program remove's extra spaces between text, so to try it enter any amount of text with lot's of space between the text's and the program would detect and truncate such space(s) to just one space
Now lets go through it. Note that we start by declaring two integer variables in the main function c and last_char_is_blank, we would use the last_char_is_blank variable, as a control variable to detect multiple spaces, We read input characters into the variable c in the while loop Next we have the if statement if(c==32) The number 32 is the ASCII value for SPACE and we could have equally done if(c== ' ') , and achieved the same result, if the character entered is a space, the if block is executed this shows that you can use any ASCII decimal value instead of an Actual character. The next line if(last_char_is_blank == 0) checks to see if the control variable has not been set the variable last_char_is_blank is initially assigned a value of zero so this test would pass and the following statements putchar(c); would be executed, the first statement outputs the space character ( remember we're still inside the if statement that detected a space) then the next statement sets our control variable last_char_is_blank to one On the next run of the loop if the imputed character is again a space, the if statement detects it, and so when the check if(last_char_is_blank == 0) is executed, the test fails since last_char_is_blank would now set to 1 (provided the previous character was a space) If the imputed character is however not a SPACE character, the first if statement fails and the else block is executed, so the non-space character gets printed. and the last_char_is_blank variable is reset to ZERO This way multiple spaces within the text is prevented. Enter the code and run-it to fully understand |
| Re: Lets Learn C by stack1(m): 11:17pm On Aug 08, 2016 |
This program count the characters, lines, and words in an input
The code is pretty self explanatory as it has been heavily commented so try to study it A new construct #define seen in the code is a pre-processor directive (similar to #include) #define is used to introduce constants (values not expected to change) into the program. As an example if you where writing a program calculating radius instead of creating an integer variable for PI like int PI = 3.142 its more appropriate to do #define PI 3.142..., so anywhere you use PI, the value 3.142 would be substituted |
| Re: Lets Learn C by stack1(m): 11:33pm On Aug 08, 2016 |
PRINT HISTOGRAM OF THE LENGTH OF EACH WORD. This next program extends the last one, we detect wen we are in a word and print a horizontal Histogram representing the length of each word //print histogram of length of each word
If you tried out the last example you'll notice the similarities, the major difference is that when we are in a word we print a horizontal bar | for each character thereby printing an Histogram for each word... more explanation in a bit, however do try it out and make sure it works |
| Re: Lets Learn C by stack1(m): 11:39pm On Aug 08, 2016 |
[size=14pt]Formatted Input/Output[/size] Now we'll learn a bit about the printf and scanf input/output functions We have been previously using the getchar and putchar functions for character input and output, while this functions work well for single character input and output many programs usually require much more complex and detailed way to get program input and output values |
| Re: Lets Learn C by timtoday: 6:06am On Aug 09, 2016 |
stack1: Hi Stack, Let me first say nice work. It is not easy to put up tutorials and as such in C programming language. The language of the gods! Lol.. I know plenty talk go start from here now! All the same, there are one or two things in my opinion that i felt is NOT sitting well as regard some of the examples you posted. At least, from this one and those that followed. Of course, there are "some-what" in the previous ones like using a char datatype to get the return value of "macro" getchar which obviously returns an integer. Of course it works because intrinsically char are "integer". And you indeed use a correct return afterwards. That been said, checking your example above, it will only take care of "spaces" whose ASCII value is 32. "Space-like" tab and others will NOT be taken care of. Secondly, using a "raw" value i.e the ASCII value will defeat clarity of codes. Yes, you commented the line, but plain integer 32 could also be used for other things IF the code is extended or for other reasons. Somehow or somewhere portability will be defeated. More so, why must I cram or have to lookup ASCII values to be able to write codes? It will further drive potential C programmer's away. Lastly, there are other difficult concepts in C already why add this to it. It is like trying to know the IP address of google instead of just using www.google.com. What do I think? Since, C, already gave us a header file <ctype.h>Let us use that to our advantage and write a more portable codes, instead of "hand-picking" values. Using such header, allows us to test more conveniently the value we are getting from standard input or file, however the case maybe. Below is rewrite of some sort...
Really, there is (might be) NO *need* for the self defined macro included but to show that allowing the language to do it work. It a lot painless some of the time. Just a note. |
| Re: Lets Learn C by timtoday: 6:23am On Aug 09, 2016 |
stack1: While the issues of ASCII value and others in my previous post still apply to this. I will like to draw your attention to this #define PI = 3.142.... Contrary to this statement so anywhere you use PI, the value 3.142 would be substituted. No your program will NOT compile! WHY? an expression is needed before the token "=". In fact, the substitute value of PI is seen from the space that follows afterwards... Probably is a typo! You are doing great boss... |
| Re: Lets Learn C by stack1(m): 8:06am On Aug 09, 2016 |
timtoday: Jesus LOL how silly of me would modify that right away, thanks |
| Re: Lets Learn C by stack1(m): 8:12am On Aug 09, 2016 |
timtoday: True and Yes was just trying to poiny out that ASCII values can also be used in plaxe of the characters them selves and as for the putchar MACRO, dats a bit too complex a statement in this stage, i actually confuse myself a lot just trying to structure the tutorial, but its good to know i have folks watching my back, and yeah C provides us several functions to do stuff i've bn trying to do manually, but i fell that would give the beginer a good hands on approach in cases they need to implement their own functions,i learnt C from Books such as K&R e.t.c so 4gv my Old school style |
| Re: Lets Learn C by stack1(m): 1:36am On Aug 16, 2016 |
Hi guyz, been a while. Sorry for the long break but i've been so busy with stuff.. Initially i thought about going into Formatted input and Output tonight, however we have covered quite some basics, so i felt why not throw in a relatively ambitious example and lets tackle it, before going into more advanced stuff Languages belonging to the C family like C (itself), C++, Java, Go, JavaScript e.t.c, have certain similar features, like they all use both single line comments
and multi-line comments
Generally comments are meant for human readers to better understand your code or to provide a means to generate documentation using various tools, so the compiler/interpreter generally ignores and discarded all comments.. The code below is an attempt at writing a Program that would remove all Single and multi-line comments from a program source code, so try it by feeding it various commented programs (not just C programs, also Java e.t.c) that you can find anywhere and lets see if it works for you.. Also try going through the code to see if you can get a hang of it, I'll be back in a few hours to go through it thoroughly. Also when testing the program after posting your code press Ctrl+Z to send the End-Of-File character as the program would keep reading input till it reaches EOF, then it processes the input and spits back your code with all comments removed..
In this example we included a new library header file you may have not seen before, stdbool.h , this header file simply introduces the Boolean types into our program, The Boolean type is a type that can hold two values either true or false, Boolean's can be used to represent state, like an [b]on [/b]or [b]off [/b]state, or 0 and 1, Yes and No, in the example we simply use it to track when we are in single and multi-line comments and when we are out of them... so please run the example and lets discuss it. The boolean type wasn't originally part of C, and was introduced in the C99 version of the language |
| Re: Lets Learn C by Nobody: 10:52am On Aug 16, 2016 |
uhm uhm, e be like say i don miss some classes, need to scroll back to previous page, it is beginning to become like magic. . . |
| Re: Lets Learn C by olarid01: 5:28pm On Aug 16, 2016 |
good job OP. I started with this language and it paid off a lot (God bless Deitel). How I wish newbies learn this language first instead of jumping to all those ready made languages full of libraries........ |
| Re: Lets Learn C by stack1(m): 5:36pm On Aug 16, 2016 |
olarid01:Quite right man, they really miss the depth, intuitive prowess C and C++ can "bestow" on a programmer, Interestingly i also had the Deitel series in hard-back (both C&C++) really good books, though i really can't remember how i misplaced them  1 Like |
| Re: Lets Learn C by stack1(m): 5:38pm On Aug 16, 2016 |
..so has anyone been able to run the comment removal program... feedback please before i dive into how it works.. |
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