#include <stdlib.h>
void	ft_putnbr_base_v2(int nbr, char *base, char *nbrf);
int		lenght_nbr(int nbr, char *base, int lenght);

int	checkerror(char *str)
{
	int	i;
	int	j;

	i = 0;
	if (str[0] == '\0' || str[1] == '\0')
		return (0);
	while (str[i] != '\0')
	{
		if ((str[i] >= 9 && str[i] <= 13) || str[i] == 32
			|| str[i] == 43 || str[i] == 45)
			return (0);
		j = i + 1;
		while (str[j] != '\0')
		{
			if (str[i] == str[j])
				return (0);
			j++;
		}
		i++;
	}
	return (i);
}

int	nb_base(char str, char *base)
{
	int	nb;

	nb = 0;
	while (base[nb] != '\0')
	{
		if (str == base[nb])
			return (nb);
		nb++;
	}
	return (-1);
}

int	whitespaces(char *str, int *ptr_i)
{
	int	count;
	int	i;

	i = 0;
	count = 1;
	while ((str[i] >= 9 && str[i] <= 13) || str[i] == 32)
		i++;
	while ((str[i] != '\0') && (str[i] == 43 || str[i] == 45))
	{
		if (str[i] == 45)
			count *= -1;
		i++;
	}
	*ptr_i = i;
	return (count);
}

int	ft_atoi_base(char *str, char *base)
{
	int	i;
	int	count;
	int	nb;
	int	nb2;
	int	base_lenght;

	nb = 0;
	i = 0;
	base_lenght = checkerror(base);
	if (base_lenght >= 2)
	{
		count = whitespaces(str, &i);
		nb2 = nb_base(str[i], base);
		while (nb2 != -1)
		{
			nb = (nb * base_lenght) + nb2;
			i++;
			nb2 = nb_base(str[i], base);
		}
		return (nb *= count);
	}
	return (0);
}

char	*ft_convert_base(char *nbr, char *base_from, char *base_to)
{
	char	*finalnbr;
	int		mednbr;
	int		lenght_nbrf;
	char	*d;

	if (checkerror(base_to) == 0 || checkerror(base_from) == 0)
		return (0);
	mednbr = ft_atoi_base(nbr, base_from);
	lenght_nbrf = lenght_nbr(mednbr, base_to, 0);
	d = (finalnbr = (char *)malloc(sizeof(char) * (lenght_nbrf + 1)));
	if (!d)
		return (0);
	ft_putnbr_base_v2(mednbr, base_to, finalnbr);
	finalnbr[lenght_nbrf] = '\0';
	return (finalnbr);
}

#include <stdio.h>
int main (int ac, char **av)
{
	(void)ac;
	printf("%s", ft_convert_base(av[1], av[2], av[3]));
}

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
}