C Programming Language Cheatsheet

C programming Cheatsheet...

Syntax (Boilerplate Code) :

#include
int main()
{
return(0);
}

printf() : printf() function for used to show the output.

printf("lapmos.com");

scanf() : scanf() function for used to take the input from users.

scanf("format_specifier", &variable);

Comments : A comment is not executed by the compiler. The comments is used for the increase the readability. In c programming language two types of comments.

1. Single Line comment

// This is single Line Comment

2. Multi Line comment

/* This is 
Multiple line 
comment
*/

Data type : Datetype is the type of data to declare the variable.

Integer Type

int variable_name;

Character Type

char var;

Float Type

float var_name;

Double Type

double variable_name;

Void Type

void

Escape Sequences : It is a sequence of characters starting with a backslash, and it doesn't represent itself when used inside string literal.

Beep / Alarm : It produce the beep sound.

\a

backspace : Add backspace

\t

New Linke : Add New line

\n

Carriage return 

\r

Tab : Gives the tab space

\t

Backslash : Add backslash

\\

Single Quote : Add single quotation mark.

\'

Question Mark : Add question mark 

\?

Octal Number : It represents the value of an octal number

\nnn

Hexadecimal Number : It represents the value of an Hexadecimal number.

\xhh

Null : The null character is usually used to terminate a string.

\0

Conditional Instructions

Conditional Statement is used to perform the logical opertion in program.

if statement

if(/* condition */){
   /* statement; */
}

if-else statement

if(/* condition */){
    /* statement*/
}
else{
    /* statement */
}

if-else-if-else statement

if(/*condition*/){
    /* statement */
}
else if(/* condition */){
    /* statement */
}
else 
{
/* statement */
}

 Switch Statement

switch(/*expression*/){
    case 1 :
        /*statement*/
    break;
    case 2 :
        /* statement */
    break;
    ....
    default :
        /* default statement */
}

Loops : 

Loops is used for , the line of code execute repatedly then programmer used loops.

for loop

for(/*initialization*/ ; /*condition*/; /*increament/decrement*/)
{
    /* code*/
}

while loop

while(/*condition*/){
    /*code*/;
}

do while loop

do{
    /* code */
}while(/*condition*/);

break statement : break keyword inside the loop is used to terminate the loop.

break;

continue statement : continue keyword skips the rest of the current iteration of the loop and returns to the starting point of the loop.

continue;

Function and Recursion : Function are used to divide the program in pieces and used function many times in our program.

Function Defination

return_type name_function(data_type parameter ...){
    // Code of the function
}

Recursion : Recursion is when a function calls itself to solve the problem. Which function is calls itself called the recursive function.

void fun(){
    ... ... .. 
    fun();
    ... ... ..
}

Pointers : Pointer is the variable which contains the address of the another variable.

data_type = *variable_name;

Array : Array is the collection of the same datatypes.

data_type array_name[array_size];

Access Element 

arr[index_no];

String : 

A string is a 1-D character Array terminated by a null character('\0')

Declaration

char string_name[string_size];

gets() function : It allows to enter the multi-word string.

gets("lapmos.com");

puts() function : It used to show the string.

puts("lapmos.com");

strlen() function : It is used for to calculate the length of string.

strlen(string_name);

strcpy() function : It is used for copy the string to another one.

strcpy(destination, source);

strcat() function : It is used for concatenate two string.

strcat(first_string, second_string);

strcmp() function : It is used for campare two string.

strcmp(first_string, second_string);

Structure : 

The Structure is a collection of different types of variable in a single. Define structure means creating a new data type.

Syntax :

struct structure_name
{
    datatype member1;
    datatype member2;
    ... .... ...
};

typedef keyword : typedef function allows user to provide alternative names for the primitive and user-defined data type.

typedef struct structure_name
{
    datatype member1;
    datatype member2;
    ...   ...  ...
}name;

 

Or

struct structure_name
{
    datatype member1;
    datatype member2;
    ...   ...  ...
};

typedef structure_name new_name;

File Handling

File handling in C enables us to create, update, read, and delete the files stored on the local file system through our C program.

FILE pointer

FILE *filepointer;

Opening a file : It is used to open file in C.

filePointer = fopen(filename.txt,w);

fscanf() function : It is used to read the content of file.

fscanf(FILE *stream, const char *format, ...);

fprintf() function : It is used to write content into the file.

fprintf(FILE *fptr, const char *str, ...);

fgetc() function : It reads a character from a file opened in read mode.

fgetc(FILE *pointer);

fputc() function : It writes a character to file opened in write mode.

fputc(char, FILE,*pointer);

Closing a File : It close the file.

fclose(filePointer);

Dynamic Memory Allocation 

The concept of dynamic memory allocation in c language enables the C programmer to allocate memory at runtime.

malloc() function : 

ptr = (TypeCast*)malloc(size());

calloc() function :

ptr = (TypeCase*)calloc(n,size);

free function : 

free(ptr);

realloc() function : 

ptr = realloc(ptr, x);

 

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Thanks......