#include <unistd.h>
void	ft_putchar(char c)
{
	write(1,&c,1);
}

int 	ft_strlen()
{
	int i;
	i = 0;
	while(str[i])
	{
		i++;
	}
	return (i);
}

int check_base(char *str)
{
	int i;
	int len;
	int j;

	len = ft_strlen(str);
	i = 0;
	while (str[i] == '\0' || len == 1)
		return (0);
	while (str[i])
	{

		if(str[i] <= 32 || str[i] == 127 || str[i] == '-' || str[i] == '+')
			return (0);
		j = i + 1;
		while (j < len)
		{
			if (str[i] == str[j])
				return (0);
			j++;
		}
	i++;
	}
return (1);

}

int		ft_atoi(char *b)
{
	int i;
	int s;
	int	res;

	res = 0;
	s = 1;
	i = 0;
	while((b[i] >= 9 && b[i] == 13) || b[i] == 32)
		i++;
	while (b[i] == '-' || b[i] == '+')
	{
		if (b[i] == '-')
			s *= -1;
		i++;
	}
	while(b[i] >= '0' && b[i] <= '9')
	{
		res = res * 10 + (b[i] -48);
		i++;
	}
return (s * res);
}
int		ft_atoi_base(char *str, char *base)
{
	int i;
	int lent;
	long n;
	i = check_base(base);
	n = ft_atoi(str);
	lent = ft_strlen(base);
	if (i == 1)
	{
		if (n < 0)
		{
			ft_putchar('-');
			n *= -1;
		}
		if (n >= len)
		{
			ft_atoi_base(n / lent , base);
			ft_atoi_base(n % lent , base);
		}
		if (n < len)
			ft_atoi_base(base[n]);
	}
	return (n);
}
int main()
{
  printf("%d",ft_atoi_base("--1457hh","01"));
}

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
}