how to reverse words in a sentence without helper methods in c++?

Question

I need to read string of characters (with spaces) and reverse it.

First i read a string of characters from console.

char array[100];

for(int i = 0; i < sizeof(array); i++)
    array[i] = '0';

for(int i = 0; i < sizeof(array); i++)
    cout<<array[i]<<" ";

cout<<"\n\nenter your string: ";

cin.getline(array, 100);

cout<<"\n";

for(int i = 0; i < sizeof(array); i++)
    cout<<array[i]<<" ";

Then i create and fill indexes array. (to remember space spots)

cout<<"\n\nindexes: ";

int indexes[20];
for(int i = 0; i < 20; i++)
{
    indexes[i] = 0;
}

// filling the indexes array
int j = 0;
for(int i = 0; i < sizeof(array); i++)
{
    if(array[i] == '0') break;
    if(array[i] == ' ')  indexes[j++] = i;
}   
// validating indexes array
for(int i = 0; i < sizeof(indexes); i++)
{
    //if(indexes[i] == 0) break;
    cout<<indexes[i]<<" ";
}

Here is the begining of my (i guess not smart) algorythm. I want to reverse first word.
Seems like this chunk never executes. Why?

// first word
int j1 = indexes[0]-1;
for(int i = 0; i > indexes[0]; i++)     
{
    new_array[i] = array[j1-i];
            cout<<"\naction\n";
}

Print new_array to console:

for(int x = 0; x < sizeof(new_array); x++)
{
    if(new_array[x] == '0') break;
    cout<<new_array[x]<<" ";
}

The result is:

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

enter your string: this is my string

t h i s i s m y s t r i n g 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

indexes: 4 7 10 17 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -858993460 -858993460 100 -85 8993460 -858993460 100 -858993460 -858993460 100 -858993460 -858993460 193628786 0 544434464 1931508077 1852404340 805314663 808464432 808464432 808464432 808464 432 808464432 808464432 808464432 808464432 808464432 808464432 808464432 808464 432 808464432 808464432 808464432 808464432 808464432 808464432 808464432 808464 432 -858993460 -742139265 6421640 18244041 1 9932784 9928256 -742139185 0 0 2129 674240 -1920 570026249 0 6422528 0 6421580 0 6421712 18223374 -759898201 0 64216 48 18244541

new array:

Why the indexes array contains these numbers after zeros? It's length is only 20.
And why the new_array is not printed?

I know that my solution is very very cumbersome)

First step: write and test a function that reverses an array of characters given a pointer to the array and its length. Step 2: use that function to reverse the little arrays that correspond to words. If you're not allowed to even call your own functions (a ridiculous requirement, if that's what is meant by "without helper methods") then manually 'inline' the function into the loop that identifies words. — Michael Burr, Dec 09 '12 at 23:20
Why the downvote? This is a legitimate question, stated clearly, with exactly the relevant code. +1 to offset. — Adam Liss, Dec 09 '12 at 23:25
[MSVC fills uninitialized memory with 0xCC to aid debugging](https://stackoverflow.com/q/370195/995714), and you have a lot of -858993460 which is 0xCCCCCCCC — phuclv, Aug 18 '18 at 11:18

score 5 · Accepted Answer · answered Dec 09 '12 at 23:23

5

Your intuition is right: the loop isn't being executed. The problem is in the line:

for(int i = 0; i > indexes[0]; i++)

The comparison should be i < indexes[0].

answered Dec 09 '12 at 23:23

Adam Liss

47,594
12
108
150

sir, excuse me, and mabby You know, why is the indexes array contains weird numbers? thanks in advance) – Aleksei Chepovoi Dec 10 '12 at 05:42

how to reverse words in a sentence without helper methods in c++?

1 Answers1