CareerCup

while(num) {
   rem  = num%10;
   num  = num/10;
   str += rem+'0';
}
return reverse(str);
//'0' -ASCII 48 to convert int to char --standard way :)

#include<stdio.h>
void reverse(char *s)
{
int i,j;
for(i=0,j=strlen(s)-1;i<j;i++,j--)
{
char t=s[i];
s[i]=s[j];
s[j]=t;
}
}
char* itoa(int n)
{
static char str[50];
int i=0;
while(n)
{
str[i++]=(n%10)+'0';
n=n/10;
}
str[i]='\0';
reverse(str);
return str;
}
main()
{
int n=1234;
char *s;
s=itoa(n);
printf("string is %s\n",s);
return 0;
}

//another solution for that problem is


#include<stdio.h>
#define max 50
char* itoa(int n)
{
static char str[max];
int i=max-1;
str[i--]='\0';
while(n)
{
str[i--]=(n%10)+'0';
n=n/10;
}
return &str[++i];
}
main()
{
int n=1234;
char *s;
s=itoa(n);
printf("string is %s\n",s);
return 0;
}

#include <stdio.h>
#include <malloc.h>

int main(){
int n=123;

// Calculate the length of integer
int length=0;
int tmp=n;

do{
 tmp=tmp/10;
 ++length;
}while(tmp!=0);

if (n<0){++length;}

// Convert it into string
char *s = (char*)malloc(sizeof(char)*(length+1));
s[length]='\0';
int i=length-1;

tmp=abs(n);
do{
 int rm = tmp%10; 
 s[i] = rm + '0';
 tmp = tmp/10;
 --i;
}while(tmp!=0);

if(n<0){s[0]='-';}
printf("%s\n",s);
return 0;
}

Running time O(n)

#include <stdio.h>
#include <malloc.h>

int main(){
int n=123;

// Calculate the length of integer
int length=0;
int tmp=n;

do{
 tmp=tmp/10;
 ++length;
}while(tmp!=0);

if (n<0){++length;}

// Convert it into string
char *s = (char*)malloc(sizeof(char)*(length+1));
s[length]='\0';
int i=length-1;

tmp=abs(n);
do{
 int rm = tmp%10; 
 s[i] = rm + '0';
 tmp = tmp/10;
 --i;
}while(tmp!=0);

if(n<0){s[0]='-';}
printf("%s\n",s);
return 0;
}

Running time O(n)

int
itoa (int num, char *str, int radix)
{
register int i, neg = 0;
register char *p = str;
register char *q = str;

if (radix == 0) radix = 10;
else if (radix < 2 || radix > RADIX_MAX) {
return (radix);
}
if (num == 0) {
*p++ = '0';
*p = 0;
return (0);
}
if (num < 0) {
neg = 1;
num = -num;
}
while (num > 0) {
i = num % radix;
if (i > 9) i += 7;
*p++ = '0' + i;
num /= radix;
}
if (neg) *p++ = '-';
*p-- = 0;
q = str;
while (p > q) {
i = *q;
*q++ = *p;
*p-- = i;
}
return (0);
}

int i = 6000;
stringstream ss<<i;
return ss.c_str();

Use sprintf
sprintf(str,"%d",a);

char *ita(int a)
{//cout<<a;
char c[10],tmp;
int i=0,a1=a,sgn=0;

if (a<0)
{ sgn=1; a*=-1; }



// cout<<a<<endl;
while(a1!=0){
a1/=10;//cout<<a1<<endl;
i++;}
// cout<<i<<endl;
for(a1=0;a1<i;a1++)
{
c[a1]=(a%10) + 48;
a/=10;
} c[i]='\0';
a1=0;i--;
cout<<c<<endl;

while(a1<i)
{
tmp=c[i];
c[i]=c[a1];
c[a1]=tmp;
a1++;
i--;
}

i=strlen(c);
if (sgn==1)
{
for(a1=strlen(c);a1>0;a1--)
{
c[a1]=c[a1-1];
}
c[0]='-';
c[i+1]='\0';
}
cout<<c;
}

I contribute a simple one.

void my_itoa(int x, char* s)
{
int base = 1;
int digit = 0;
int y = x;

while(y>0 && y/10>0)
{
base*=10;
y = y/10;
}

y = x;

while(base>0)
{
digit = y/base;
*s++ = digit + '0';
y-=digit*base;
base/=10;
}

*s = '\0';
}

This considers value 0 and < 0 too

void myitoa(int int_val, char * str)
{
	int abs_val = int_val ;
	char tmp_str [32] ;
	int str_index = 31 ;

	if (int_val == 0 )
	{
		strcpy(str, "0") ;
		return ;
	}

	abs_val = abs( int_val ) ;
	
	tmp_str[str_index--] = '\0' ;
	
	while(abs_val)
	{
		int cur_digit ;

		cur_digit = abs_val % 10 ;
		abs_val /= 10 ; 

		tmp_str[str_index--] = cur_digit + '0' ;
	}
	
	if( int_val <0 )
	{
		tmp_str [str_index] = '-' ;
		strcpy ( str, tmp_str + str_index ) ; 
	}
	else
	{
		strcpy ( str, tmp_str + str_index + 1 ) ; 
	}
	
}

Easy, in C# :-)

string itoa(int n) {
    return n.ToString();
}