Exercises 3-4

#include <stdio.h>#define abs(x) ((x)<0?-(x):(x))void itoa(int n,char s[]);void reverse(char s[]);int main(int argc, char *argv[]){    char s[300];    int n=5201314;    itoa(n,s);    printf("%s\n",s);    return 0;}void itoa(int n,char s[]){    int sign=n;    int i=0;    do    {        s[i++]=abs(n%10)+'0';    }    while((n/=10)!=0);    if(sign<0)        s[i++]='-';    s[i]='\0';    reverse(s);}void reverse(char s[]){    int i=0,j;    int len=0;    while(s[i++]!='\0')        len++;    if(len>1)    {        char c;        j=len-1;        i=0;        while(i<j)        {            c=s[i];            s[i]=s[j];            s[j]=c;            i++;            j--;        }    }}