#include <stdio.h>
#include <stdlib.h>

#define SIZE 10

// Define the structure for a hash table
struct HashTable {
    int keys[SIZE];
    int values[SIZE];
    int occupied[SIZE];
};

// Function to initialize the hash table
void initialize(struct HashTable *table) {
    for (int i = 0; i < SIZE; i++) {
        table->keys[i] = -1;  // -1 indicates an empty slot
        table->values[i] = -1;
        table->occupied[i] = 0;  // 0 indicates the slot is unoccupied
    }
}

// Hash function to calculate the index
int hash(int key) {
    return key % SIZE;
}

// Function to insert a key-value pair into the hash table
void insert(struct HashTable *table, int key, int value) {
    int index = hash(key);

    while (table->occupied[index]) {
        index = (index + 1) % SIZE;
    }

    table->keys[index] = key;
    table->values[index] = value;
    table->occupied[index] = 1;
}

// Function to search for a value based on a given key
int search(struct HashTable *table, int key) {
    int index = hash(key);

    while (table->occupied[index]) {
        if (table->keys[index] == key) {
            return table->values[index];
        }
        index = (index + 1) % SIZE;
    }

    return -1; // Not found
}

int main() {
    struct HashTable table;
    initialize(&table);

    // Insert key-value pairs
    insert(&table, 10, 100);
    insert(&table, 20, 200);
    insert(&table, 30, 300);
    insert(&table, 40, 400);

    // Search for values
    int value1 = search(&table, 10);
    int value2 = search(&table, 30);
    int value3 = search(&table, 50);

    printf("Value for key 10: %d\n", value1); // Expected output: 100
    printf("Value for key 30: %d\n", value2); // Expected output: 300
    printf("Value for key 50: %d\n", value3); // Expected output: -1 (not found)

    return 0;
}

C Language online compiler

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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
}