#include <stdlib.h>
char    *ft_substr(char const *s, unsigned int start, size_t len)
{
    char    *substr;

    substr = (char *)malloc(len + 1);
    if (substr == NULL)
        return (NULL);
    if (ft_strlen(s) <= start)
        return ("");
    substr = (char *)ft_memcpy(substr, &s[start], len);
    substr[len] = '\0';
    return (substr);
}
void    *ft_memcpy(void *dst, const void *src, size_t n)
{
    char    *dest;
    char    *sourc;
    int    i;

    dest = (char *)dst;
    sourc = (char *) src;
    i = 0;
    if (dest == NULL && sourc == NULL)
        return (NULL);
    while (i < n)
    {
        dest[i] = sourc[i];
        i++;
    }
    return (dst);
}
int    ft_strlen(const char *s)
{
    int    len;

    len = 0;
    while (s[len] != '\0')
        len++;
    return (len);
}
static int    ft_isit(char const *set, int c)
{
    while (*set != '\0')
    {
        if (*set == c)
            return (1);
        set++;
    }
    return (0);
}

char    *ft_strtrim(char const *s1, char const *set)
{
    char    *arr;
    int        len;

    len = ft_strlen(s1);
    while (*s1 != '\0' && ft_isit(set, *s1))
    {
        s1++;
        len--;
    }
    while (ft_isit(set, s1[len - 1]))
        len--;
    arr = ft_substr(s1, 0, len);
    return (arr);
}

int main()
{
    char s1[] = "          ";
    printf("%s", ft_strtrim(s1, " "));
}

C Language online compiler

Write, Run & Share C Language code online using OneCompiler's C online compiler for free. It's one of the robust, feature-rich online compilers for C language, running the latest C version which is C18. Getting started with the OneCompiler's C editor is really simple and pretty fast. The editor shows sample boilerplate code when you choose language as 'C' and start coding!

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
}