Some small C programs written as homeworks

calendar.c

/*
 * wap
 * kalendari per 1 muaj
 * perdoruesi jep vitin dhe muajin
 */

#include <stdio.h>

int main(int argc,char **argv) {
	char* s_muaji[] = {"Janar","Shkurt","Mars","Prill","Maj","Qershor","Korrik","Gusht","Shtator","Tetor","Nentor","Dhjetor"};
	
	int viti,muaji,shekulli,v_shek;
	int nr_dit,fillimi,i;
	int count;
	int flag = 7; /* flag per te kontrolluar nqs eshte arritur e diela e pare e muajit */
	
	if (argc != 3) {
		printf("Perdorimi: calendar viti muaji\n");
		return 1;
	}
	
	/* lexo vitin */
	viti = atoi(argv[1]);
	
	/* percaktojme shekullin dhe vitin e shekullit qe i perket ky vit */
	shekulli = (int) viti/100;
	v_shek = viti % 100;
	
	/* lexo muajin */
	muaji = atoi(argv[2]);
	
	printf("Kalendari per muajin %s te vitit %d\n\n",s_muaji[muaji-1],viti);
	
	/* percaktojme numrin e diteve */
	switch(muaji) {
		case 1: /* janar */
		case 3: /* mars */
		case 5: /* maj */
		case 7: /* korrik */
		case 8: /* gusht */
		case 10: /* tetor */
		case 12: /* dhjetor */
			nr_dit = 31;
			break;
			
		case 2: /* shkurti ka 29 dite ne vit te brishte, 28 ne vite te tjera */
			if((viti%4==0 && viti%100 != 0) || (viti%400==0)) /* vit i brishte */
				nr_dit=29;
			else nr_dit=28;
			break;
		
		default:
			nr_dit=30;
	}
	
	/* rregullim per shkak te formules: Janari eshte muaji 13 dhe Shkurti muaji 14 */
	if(muaji<3) muaji+=12; 
	
	
	/* gjejme cfare dite e javes eshte dita e pare e muajit */
	fillimi = (1 + 26*(muaji+1)/10 + v_shek + v_shek/4 + shekulli/4 + 5*shekulli)%7;
	
	/* rregullim per shkak te formules: Java fillon me te shtunen */
	switch(fillimi) {
		case 0: /* e shtune */
		case 1: /* e diel */
			fillimi+=5;
			break;
		default:
			fillimi-=2;
	}
	
	/* printo header */
	printf("  H  M  M  E  P  S  D\n");
	printf("---------------------\n");
	
	flag -= fillimi;
	
	/* printo hapesirat per te zhvendosur ne te djathte ditet e javes */
	for (i=0;i<fillimi;i++) printf("%3c",' '); 
	
	for (i=1,count=i;i<=nr_dit;i++,count++) {
		printf("%3d",i);
		if (count==flag) {
			count=0;
			printf("\n");
			flag = 7;
		}
	}
	return 0;
}

palindrome.c

/* 10. Palindrome string */
#include <stdio.h>
#include <string.h>

int palindrome(char* s) {
	int i=0,l=strlen(s);
	int upto=l/2+1;
	for (;i<upto;i++) 
		if (s[i]!=s[l-i-1]) return 0;
	return 1;
}

int main(void) {
	char *str;
	printf("Test if this is palindrome: ");
	gets(str);
	palindrome(str) ? printf("%s is palindrome\n",str) : printf("%s is not palindrome\n",str);
	return 0;
}

pow_of_two.c

/* 30. Power of 2 */

#include <stdio.h>

int power2(int n) {
	do {
		if (n%2==0) {
			n/=2;
			power2(n);
		}
		else return 0;
	} while (n>2);
	return 1;
}

int main(void) {
	int p;
	printf("p=");
	scanf("%d",&p);
	power2(p) ? printf("%d is power of 2",p) : printf("%d is not power of 2",p);
	return 0;
}

strcat.c

/* 15. String concatenate */

#include <stdio.h>

void concatenate(char *s1,char *s2) {
	sprintf(s1,"%s%s",s1,s2);
}

int main(void) {
	char *s1,*s2;
	printf("s1: ");
	gets(s1);
	printf("s2: ");
	gets(s2);
	concatenate(s1,s2);
	printf("%s",s1);
	return 0;
}

strcmp.c

/* 14. String compare */

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

int equal_str(char *s1,char *s2) {
	int l1=strlen(s1);
	int l2=strlen(s2);
	int i;
	/* if string dont have the same length, they are not equal */
	if (l1!=l2) return 0;
	
	for (i=0;i<l1;i++) 
		if (s1[i]!=s2[i]) return 0;
	
	return 1;
}

int main(void) {
	char *s1,*s2;
	printf("s1: ");
	gets(s1);
	printf("s2: ");
	gets(s2);
	equal_str(s1,s2) ? printf("both strings are equal\n") : printf("strings are not equal");
	return 0;
}

swap_w_temp.c

/* 3. Swap with temp */

#include <stdio.h>

void swap(int* a,int* b) {
	int temp;
	temp=*a;
	*a=*b;
	*b=temp;
}

int main(void) {
	int n1,n2;
	printf("n1=");
	scanf("%d",&n1);
	printf("n2=");
	scanf("%d",&n2);
	swap(&n1,&n2);
	printf("n1=%d n2=%d",n1,n2);
	return 0;
}

swap_w_xor.c

/* 5. Swap with xor */

#include <stdio.h>

void swap(int *a,int *b) {
	if (a!=b) {
		*a ^= *b;
		*b ^= *a;
		*a ^= *b;
	}
}

int main(void) {
	int a,b;
	printf("a="); scanf("%d",&a);
	printf("b="); scanf("%d",&b);
	swap(&a,&b);
	printf("a=%d, b=%d",a,b);
	return 0;
}

swap_wout_temp.c

/* 4. Swap without temp */

#include <stdio.h>

void swap(int *a,int *b) {
	*a-=*b;
	*b+=*a;
	*a=(*b - *a);
}

int main(void) {
	int a,b;
	printf("a="); scanf("%d",&a);
	printf("b="); scanf("%d",&b);
	swap(&a,&b);
	printf("a=%d, b=%d",a,b);
	return 0;
}

time_counter.c

#include <stdio.h>
#include <time.h>

int main(void) {
    time_t start,cont;
    int seconds,counter=0;
    double d;
    printf("Enter time to delay: ");
    scanf("%d",&seconds);
    printf("Time started\n");
    printf("%d  ",counter);
    time(&start);
    do {
        time(&cont);
        d=difftime(cont,start);
        if (d==1.0) {
                  counter++;
                  printf("%d  ",counter);
                  time(&start);
                  }
        else continue;
    } while(counter<seconds);
    printf("\nCounting ended");
    return 0;
}