#include <stdio.h>
#include <stdlib.h>
#define NO_OF_CHARS 256
 
/* Returns an array of size 256 containing count

   of characters in the passed char array */

int* getCharCountArray(char* str)
{

    int* count = (int*)calloc(sizeof(int), NO_OF_CHARS);

    int i;

    for (i = 0; *(str + i); i++)

        count[*(str + i)]++;

    return count;
}
 
/* removeDirtyChars takes two 
string as arguments: First
string (str)  is the one from
where function removes dirty
characters. Second  string is
the string which contain all
dirty characters which need to 
be removed  from first string
*/

char* removeDirtyChars(char* str, char* mask_str)
{

    int* count = getCharCountArray(mask_str);

    int ip_ind = 0, res_ind = 0;

    while (*(str + ip_ind))

    {

        char temp = *(str + ip_ind);

        if (count[temp] == 0) 

        {

            *(str + res_ind) = *(str + ip_ind);

            res_ind++;

        }

        ip_ind++;

    }
 

    /* After above step string is ngring.

      Removing extra "iittg" after string*/

    *(str + res_ind) = '\0';
 

    return str;
}
 
/* Driver code*/

int main()
{

    char str[] = "programming";

    char mask_str[] = "ra";

    printf("%s", removeDirtyChars(str, mask_str));

    return 0;
}
by

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Read inputs from stdin

OneCompiler's C online editor supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample C program which takes name as input and print your name with hello.

#include <stdio.h>
int main()
{
    char name[50];
    printf("Enter name:");
    scanf("%s", name);
    printf("Hello %s \n" , name );
    return 0;
    
}

About C

C language is one of the most popular general-purpose programming language developed by Dennis Ritchie at Bell laboratories for UNIX operating system. The initial release of C Language was in the year 1972. Most of the desktop operating systems are written in C Language.

Key features:

  • Structured Programming
  • Popular system programming language
  • UNIX, MySQL and Oracle are completely written in C.
  • Supports variety of platforms
  • Efficient and also handle low-level activities.
  • As fast as assembly language and hence used as system development language.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition if-else is used.

if(conditional-expression) {
   // code
} else {
   // code
}

You can also use if-else for nested Ifs and if-else-if ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to if-else-if ladder.

switch(conditional-expression) {    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
...    
    
default:     
 // code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  // code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition) {  
 // code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {
  // code 
} while (condition);

Arrays

Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.

Syntax

One dimentional Array:

data-type array-name[size];

Two dimensional array:

data-type array-name[size][size];

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity.

Two types of functions are present in C

  1. Library Functions:

Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,

  1. User defined functions:

User defined functions are the ones which are written by the programmer based on the requirement.

How to declare a Function

return_type function_name(parameters);

How to call a Function

function_name (parameters)

How to define a Function

return_type function_name(parameters) {  
  //code
}