CareerCup

One of many possible implementations.

template<class T>
void swap(T& a, T& b)
{
    a^=b;
    b^=a;
    a^=b;
}

char* reverseString(char* pStr, int size)
{
    if( !pStr ) return 0;
    char* pBeg=pStr;
    char* pEnd=pStr+size-1;
    while( pBeg < pEnd )
    {
        swap(*pBeg++,*pEnd--);
    }
    return pStr;
}

No temporary memory needed,

char* reverse(char* str)
{
int i=0,len=strlen(str);
while(i<len/2)
{
str[i]=str[i]+str[len-i-1];
str[len-i-1]=str[i]-str[len-i-1];
str[i]=str[i]-str[len-i-1];
i++;
}
std::cout<<str;
return str;
}

void main()
{
char s[12]= "hello world";
reverse(s);
}

we're not asked to use C/Java etc so this is my take in python in a single line,

reversedString = givenString[::-1]

and you are done!

#include<stdio.h>
#include<string.h>
main()
{
char a[10],temp;
scanf("%s",a);
int l=strlen(a),i;
int k=l-1;
for(i=0;i<l/2;i++)
{
temp=a[i];
a[i]=a[k];
a[k]=temp;
k--;
}
printf("%s\n",a);
}

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


void reverseString(char *str);


void reverseString(char *str){
int len=0;
if (!str || (len=strlen(str))<2)
return;
int i;
for(i=0; i<len>>1; i++)
{
str[i]=str[i]+str[len-1-i];
str[len-1-i]=str[i]-str[len-1-i];
str[i]=str[i]-str[len-1-i];
}

}

int main (int argc, const char * argv[]) {

char str1[100]={0};
char str2[100]={0};

strcpy(str1, "Hello World");
strcpy(str2, str1);
reverseString(str1);
printf("in:%s\t\t out:%s\n", str2, str1);

strcpy(str1, "abc");
strcpy(str2, str1);
reverseString(str1);
printf("in:%s\t\t out:%s\n", str2, str1);

strcpy(str1, "ab");
strcpy(str2, str1);
reverseString(str1);
printf("in:%s\t\t out:%s\n", str2, str1);

//strcpy(str1, NULL);
//strcpy(str2, str1);
reverseString(NULL);
printf("in:%s\t\t out:%s\n", NULL, NULL);

strcpy(str1, "a");
strcpy(str2, str1);
reverseString(str1);
printf("in:%s\t\t out:%s\n", str2, str1);

return 0;
}

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


void reverseString(char *str);


void reverseString(char *str){
int len=0;
if (!str || (len=strlen(str))<2)
return;
int i;
for(i=0; i<len>>1; i++)
{
str[i]=str[i]+str[len-1-i];
str[len-1-i]=str[i]-str[len-1-i];
str[i]=str[i]-str[len-1-i];
}

}

int main (int argc, const char * argv[]) {

char str1[100]={0};
char str2[100]={0};

strcpy(str1, "Hello World");
strcpy(str2, str1);
reverseString(str1);
printf("in:%s\t\t out:%s\n", str2, str1);

strcpy(str1, "abc");
strcpy(str2, str1);
reverseString(str1);
printf("in:%s\t\t out:%s\n", str2, str1);

strcpy(str1, "ab");
strcpy(str2, str1);
reverseString(str1);
printf("in:%s\t\t out:%s\n", str2, str1);

//strcpy(str1, NULL);
//strcpy(str2, str1);
reverseString(NULL);
printf("in:%s\t\t out:%s\n", NULL, NULL);

strcpy(str1, "a");
strcpy(str2, str1);
reverseString(str1);
printf("in:%s\t\t out:%s\n", str2, str1);

return 0;
}

#include<stdio.h>
#include<string.h>
int main()
{
char s[30]="utam",t;
int i,j;
i=0;j=strlen(s)-1;
while(!((i==j)||(i>j)))
{
//printf("hi\n");
t=s[i];
s[i]=s[j];
s[j]=t;
i++;j--;
}
printf("%s\n",s);
}