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#include<iostream.h>
#include<string.h>


// with pointers
void myStrCat1(char *s1, const char *s2)
{
	// boro jelo taa be sefre paayaane
	// reshte beresi
	while (*s1) 
		s1++;

	// boto jelo taa be sefre paayane reshteye
	// s2 beresi, copy kon
	while (*s2) {
		*s1 = *s2;
		s2++;
		s1++;
	}

	// sefre payan reshte be s1 ezaafe ko
	*s1 = '\0';
}

// with arrays
void myStrCat2(char s1[], const char s2[])
{
	int i, j;
	for (i=0 ; s1[i] ; i++);
	for (j=0 ; s2[j] ; i++,j++)
		s1[i] = s2[j];
	s1[i] = '\0';
}


// with arrays, AND strlen
void myStrCat3(char s1[], const char s2[])
{
	int i, j;
	i = strlen(s1);
	for (j=0 ; s2[j] ; i++,j++)
		s1[i] = s2[j];
	s1[i] = '\0';
}


void main ()
{
	char esm1[80] = "ali";
	char esm2[80] = "gholi";
	myStrCat1(esm1, esm2);
	myStrCat2(esm1, esm2);
	myStrCat3(esm1, esm2);
	cout << esm1 << endl;

}