#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

/* convert unsigned integer to decimal format string and 
 * store it in buffer */
void convert_i_str(int number, char * buffer){
	int n, index = 0, len = 0, tmp;

	tmp = number;
	while (number != 0) {
		number = number / 10;
		len++;
	}

	number = tmp;
	while(number != 0) {
		n = number % 10; 
		buffer[len - index - 1] = n + '0';
		number = number / 10;
		index++;
	}
	buffer[index] = '\0';
}

int main(){
	char buffer[1000];
	int fd = open("./test.txt", O_RDONLY);
	ssize_t bytesread = read(fd, buffer, 1000);

	char *p = &buffer[5];
	int number = atoi(p);
	number = number + 100;
	char buffer2[100];
	convert_i_str(number, buffer2);
	write(1, buffer2, strlen(buffer2));
	write(1, "\n", 1);
	close(fd);
}