/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   ft_substr.c                                       :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: lcherng- <[email protected]>    +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2023/10/16 10:57:41 by lcherng-          #+#    #+#             */
/*   Updated: 2023/10/16 10:59:15 by lcherng-         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

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

char	*ft_substr(char const *s, unsigned int start, size_t len);

char	*ft_substr(char const *s, unsigned int start, size_t len)
{
	char	*sub;
	int		i;

	sub = (char *)malloc((len + 1));
	i = -1;
	if (sub != NULL)
	{
		while (++i < len && s[start] != '\0')
		{
			printf("%c\n", s[start]);
			sub[i] = s[start];
			start++;
		}
		sub[i] = '\0';
	}
	return (sub);
}

int	main(void)
{
	const char *inputString = "Hello, World!";
	unsigned int start;
	size_t length;
	char *result;

	// Test Case 1: Extract substring from index 7 with length 5
	start = 7;
	length = 5;
	result = ft_substr(inputString, start, length);
	printf("Test Case 1: %s\n", result); // Expected Output: "World"
	free(result);                       
		// Don't forget to free the allocated memory

	// Test Case 2: Extract substring from index 0 with length 13 (entire string)
	start = 0;
	length = strlen(inputString);
	result = ft_substr(inputString, start, length);
	printf("Test Case 2: %s\n", result); // Expected Output: "Hello, World!"
	free(result);

	// Test Case 3: Extract substring from index 14 with length 2 (out of bounds)
	start = 14;
	length = 2;
	result = ft_substr(inputString, start, length);
	printf("Test Case 3: %s\n", result); // Expected Output: ""
	free(result);

	// Test Case 4: Extract substring from index 6 with length 0 (empty substring)
	start = 6;
	length = 0;
	result = ft_substr(inputString, start, length);
	printf("Test Case 4: %s\n", result); // Expected Output: ""
	free(result);

	// Test Case 5: Extract substring from index 20 with length 5 (out of bounds)
	start = 20;
	length = 5;
	result = ft_substr(inputString, start, length);
	printf("Test Case 5: %s\n", result); // Expected Output: ""

	return (0);
}

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Read inputs from stdin

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#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
}