diff options
| -rw-r--r-- | c.html.markdown | 53 |
1 files changed, 25 insertions, 28 deletions
diff --git a/c.html.markdown b/c.html.markdown index fd0b7964..89bfbe6d 100644 --- a/c.html.markdown +++ b/c.html.markdown @@ -39,7 +39,7 @@ Multi-line comments look like this. They work in C89 as well. //print formatting: "%d" // integer -"%3d" // minimum length of 3 digits for integer (right justifies text) +"%3d" // integer with minimum of length 3 digits (right justifies text) "%s" // string "%f" // float "%ld" // long @@ -51,7 +51,7 @@ Multi-line comments look like this. They work in C89 as well. "%o" // octal "%%" // prints % -// Constants: use #define keyword, no semicolon at end. +// Constants: #define <keyword> (no semicolon at end) #define DAYS_IN_YEAR = 365 //enumeration constants are also ways to declare constants. @@ -62,7 +62,6 @@ enum days {SUN = 1, MON, TUE, WED, THU, FRI, SAT}; #include <stdlib.h> #include <stdio.h> #include <string.h> -#include <ctype.h> // (File names between <angle brackets> are headers from the C standard library.) // For your own headers, use double quotes instead of angle brackets: @@ -111,7 +110,7 @@ int main() { unsigned int ux_int; unsigned long long ux_long_long; - // chars inside single quotes '*' are integers in your character set. + // chars inside single quotes are integers in machine's character set. '0' //==> 48 on the ASCII character set. 'A' //==> 65 on the ASCII character set. @@ -226,20 +225,14 @@ int main() { 0 || 1; // => 1 (Logical or) 0 || 0; // => 0 - //Conditional expression ( ?: ) + //Conditional expression ( ? : ) int a, b, z; - z = (a > b) ? a : b; // z = max(a, b); + z = (a > b) ? a : b; // "if a > b return a, else return b." //Increment and decrement operators: - int j = 0; - char s[]; - int w = 0; - j++; //difference between postfix and prefix explained below - ++j; // in string example. - j--; - --j; s[j++]; //returns value of j to s THEN increments value of j. s[++j]; //increments value of j THEN returns value of j to s. + // same with j-- and --j // Bitwise operators! ~0x0F; // => 0xF0 (bitwise negation, "1's complement") @@ -267,12 +260,6 @@ int main() { printf("I print\n"); } - // Notes: - // Loops MUST always have a body. If no body is needed, do this: - for (i = 0; i <= 5; i++) { - ; // use semicolon to act as the body (null statement) - } - // While loops exist int ii = 0; while (ii < 10) { //ANY value not zero is true. @@ -297,6 +284,12 @@ int main() { printf("\n"); + // *****NOTES*****: + // Loops MUST always have a body. If no body is needed, do: + for (i = 0; i <= 5; i++) { + ; // use semicolon to act as the body (null statement) + } + // branching with multiple choices: switch() switch (some_integral_expression) { case 0: // labels need to be integral *constant* epxressions @@ -448,18 +441,20 @@ int add_two_ints(int x1, int x2) return x1 + x2; // Use return to return a value } -// Must declare a 'funtion prototype' before main() when creating functions -// in file. +// Must declare a 'funtion prototype' when creating functions before main() void getInt(char c); // function prototype -int main() { +int main() { // main function return 0; } void getInt(char w) { //parameter name does not need to match function prototype ; } -//if function takes no parameters, do: int getInt(void); for function prototype -// and for the function declaration: int getInt(void) {} -// this is to keep compatibility with older versions of C. + +//if function takes no parameters, do: +int getInt(void); for function prototype +// and for the function declaration: +int getInt(void) {} +// (this is to keep compatibility with older versions of C). /* Functions are call by value. So when a function is called, the arguments passed @@ -485,11 +480,13 @@ void str_reverse(char *str_in) } } +///////////////////////////////////// // Built in functions: +///////////////////////////////////// // from stdio.h: -int c = getchar(); //reads character from input. If input = hi, only h is read. -// getchar() can be stored into int or char. I am using int because -// char is not large enough to store EOF used below. +// getchar() +int c = getchar(); //reads character from input. +// If input = hi, 'h' is returned then next call, 'i' returned. while ((c = getchar()) != EOF) { // EOF constant "end of file". // Linux: CTRL+D, Windows: CTRL+X // must have () around getchar() as != is run before =. |