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

// Function prototypes (assuming these functions are already implemented)
char	*ft_strtrim(char const *s1, char const *set);
size_t	ft_strlen(const char *s);
char	*ft_strdup(const char *s1);
void	*ft_memcpy(void *dst, const void *src, size_t n);
char	*ft_strchr(const char *s, int c);

int	main(void)
{
    char *s1 = "ello, World!   ";
    char *set = " ";
    char *trimmed_str;

    trimmed_str = ft_strtrim(s1, set);
    if (trimmed_str != NULL)
    {
        printf("Original string: '%s'\n", s1);
        printf("Set of characters to trim: '%s'\n", set);
        printf("Trimmed string: '%s'\n", trimmed_str);
        free(trimmed_str);
    }
    else
    {
        printf("Error: ft_strtrim returned NULL\n");
    }

    return 0;
}

// Dummy implementations for required functions
size_t ft_strlen(const char *s)
{
    size_t len = 0;
    while (s[len] != '\0')
        len++;
    return len;
}

char *ft_strdup(const char *s1)
{
    size_t len = ft_strlen(s1);
    char *dup = malloc(len + 1);
    if (dup)
    {
        ft_memcpy(dup, s1, len);
        dup[len] = '\0';
    }
    return dup;
}

void *ft_memcpy(void *dst, const void *src, size_t n)
{
    char *d = dst;
    const char *s = src;
    while (n--)
        *d++ = *s++;
    return dst;
}

char *ft_strchr(const char *s, int c)
{
    while (*s != '\0')
    {
        if (*s == c)
            return (char *)s;
        s++;
    }
    if (c == '\0')
        return (char *)s;
    return NULL;
}
char	*ft_strtrim(char const *s1, char const *set)
{
	size_t	start;
	size_t	end;
	size_t	size;
	char	*str;

	if (set == NULL || s1 == NULL)
		return ((char *)s1);
	start = 0;
	while (ft_strchr(set, s1[start]) != NULL && s1[start] != '\0')
		start++;
	end = ft_strlen(s1) - 1;
	while (ft_strchr(set, s1[end]) != NULL && end > start)
		end--;
	size = end - start + 1;
	if (size <= 0)
		return (ft_strdup(""));
	str = malloc((size + 1) * sizeof(char));
	if (str == NULL)
		return (NULL);
	ft_memcpy((void *)str, (void *)&s1[start], size);
	str[size] = '\0';
	return (str);
}
by

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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
}