diff options
Diffstat (limited to 'c.html.markdown')
| -rw-r--r-- | c.html.markdown | 67 |
1 files changed, 64 insertions, 3 deletions
diff --git a/c.html.markdown b/c.html.markdown index 5e8e13c1..7bb363b3 100644 --- a/c.html.markdown +++ b/c.html.markdown @@ -6,7 +6,12 @@ contributors: - ["Árpád Goretity", "http://twitter.com/H2CO3_iOS"] - ["Jakub Trzebiatowski", "http://cbs.stgn.pl"] - ["Marco Scannadinari", "https://marcoms.github.io"] +<<<<<<< HEAD - ["Zachary Ferguson", "https://github.io/zfergus2"] +======= + - ["himanshu", "https://github.com/himanshu81494"] + +>>>>>>> refs/remotes/adambard/master --- Ah, C. Still **the** language of modern high-performance computing. @@ -27,6 +32,7 @@ Multi-line comments don't nest /* Be careful */ // comment ends on this line... */ // ...not this one! // Constants: #define <keyword> +// Constants are written in all-caps out of convention, not requirement #define DAYS_IN_YEAR 365 // Enumeration constants are also ways to declare constants. @@ -52,10 +58,21 @@ int function_2(void); // Must declare a 'function prototype' before main() when functions occur after // your main() function. int add_two_ints(int x1, int x2); // function prototype +// although `int add_two_ints(int, int);` is also valid (no need to name the args), +// it is recommended to name arguments in the prototype as well for easier inspection // Your program's entry point is a function called // main with an integer return type. int main(void) { + // your program +} + +// The command line arguments used to run your program are also passed to main +// argc being the number of arguments - your program's name counts as 1 +// argv is an array of character arrays - containing the arguments themselves +// argv[0] = name of your program, argv[1] = first argument, etc. +int main (int argc, char** argv) +{ // print output using printf, for "print formatted" // %d is an integer, \n is a newline printf("%d\n", 0); // => Prints 0 @@ -63,6 +80,9 @@ int main(void) { /////////////////////////////////////// // Types /////////////////////////////////////// + + // All variables MUST be declared at the top of the current block scope + // we declare them dynamically along the code for the sake of the tutorial // ints are usually 4 bytes int x_int = 0; @@ -221,7 +241,7 @@ int main(void) { 0 || 1; // => 1 (Logical or) 0 || 0; // => 0 - // Conditional expression ( ? : ) + // Conditional ternary expression ( ? : ) int e = 5; int f = 10; int z; @@ -291,6 +311,8 @@ int main(void) { for (i = 0; i <= 5; i++) { ; // use semicolon to act as the body (null statement) } + // Or + for (i = 0; i <= 5; i++); // branching with multiple choices: switch() switch (a) { @@ -306,7 +328,29 @@ int main(void) { exit(-1); break; } - + /* + using "goto" in C + */ + typedef enum { false, true } bool; + // for C don't have bool as data type :( + bool disaster = false; + int i, j; + for(i=0;i<100;++i) + for(j=0;j<100;++j) + { + if((i + j) >= 150) + disaster = true; + if(disaster) + goto error; + } + error : + printf("Error occured at i = %d & j = %d.\n", i, j); + /* + https://ideone.com/GuPhd6 + this will print out "Error occured at i = 52 & j = 99." + */ + + /////////////////////////////////////// // Typecasting /////////////////////////////////////// @@ -472,7 +516,24 @@ char c[] = "This is a test."; str_reverse(c); printf("%s\n", c); // => ".tset a si sihT" */ - +/* +as we can return only one variable +to change values of more than one variables we use call by reference +*/ +void swapTwoNumbers(int *a, int *b) +{ + int temp = *a; + *a = *b; + *b = temp; +} +/* +int first = 10; +int second = 20; +printf("first: %d\nsecond: %d\n", first, second); +swapTwoNumbers(&first, &second); +printf("first: %d\nsecond: %d\n", first, second); +// values will be swapped +*/ // if referring to external variables outside function, must use extern keyword. int i = 0; void testFunc() { |