坚持从字符串中删除空格而不使用任何帮助代码 c++

Question

Create a program titled str_compress.cpp. This program will take a sentence input and remove all spaces from the sentence. (A good first step in encryption programs) Make sure that both the input and output strings are all stored in a single variable each. Do not use numbers or symbols. Include both upper-case and lower-case letters. Account for cases with multiple spaces anywhere.

This is what I have so far:

#include <iostream>
#include <string>
using namespace std;

int main()
{
    int i = 0, j = 0, len;
    string str;

    cout << "Enter string: ";
    getline(cin, str);

    len = str.length();

    for (i = 0; i < len; i++)
    {
        if (str[i] == ' ')
        {
            for (j = i; j < len; j++)
            {
                str[j] = str[j + 1];
            }
            len--;
        }
    }

    cout << str << endl;

    system("pause");
    return 0;
}

I can eliminate spaces, but only one at a time. If I copy and paste the for loop, I can remove all spaces for how many loops there are. I'm thinking that I can loop the for loop over and over until all spaces are gone, but I'm not sure how to do that. Also, I can't use anything like remove_all() or erase() .

Answer 1

This is a strong clue for how the authors of your exercise want you to write your code:

Make sure that both the input and output strings are all stored in a single variable each

You should make a new string:

string new_str;

Use your loop over the input string. For each char in the string, check whether it is a space. If yes, do nothing. If no, append it to the output string:

for (i = ...)
{
    char c = str[i];
    if (c != ' ')
        new_str.push_back(c);
}

Answer 2

Your loop's logic when removing a space is wrong. For instance, after removing a space, you then skip the next char in the string, which may be another space. Also, although you are decrementing the len , you don't resize the string to the new len before printing the new str value.

It should look more like this:

#include <iostream>
#include <string>
using namespace std;

int main()
{
    size_t i, j, len;
    string str;

    cout << "Enter string: ";
    getline(cin, str);

    len = str.length();

    i = 0;
    while (i < len)
    {
        if (str[i] == ' ')
        {
            for (j = i + 1; j < len; ++j)
            {
                str[j - 1] = str[j];
            }
            --len;
        }
        else
            ++i;
    }

    str.resize(len);
    cout << str << endl;

    /* or, if you are not allowed to use resize():
    cout.write(str.c_str(), len);
    cout << endl;
    */

    /* or, if you are not allowed to use write():
    if (len < str.length())
        str[len] = '\0';
    cout << str.c_str() << endl;
    */

    system("pause");
    return 0;
}

Live Demo

However, your instructions do say to " Make sure that both the input and output strings are all stored in a single variable each ", which implies that separate std::string variables should be used for input and output, eg:

#include <iostream>
#include <string>
using namespace std;

int main()
{
    size_t i, j, len;
    string str, str2;

    cout << "Enter string: ";
    getline(cin, str);

    str2 = str;
    len = str2.length();

    i = 0;
    while (i < len)
    {
        if (str2[i] == ' ')
        {
            for (j = i + 1; j < len; ++j)
            {
                str2[j - 1] = str2[j];
            }
            --len;
        }
        else
            ++i;
    }

    str2.resize(len);
    cout << str2 << endl;

    /* or:
    cout.write(str2.c_str(), len);
    cout << endl;
    */

    /* or:
    if (len < str2.length())
        str2[len] = '\0';
    cout << str2.c_str() << endl;
    */

    system("pause");
    return 0;
}

Live Demo

Alternatively:

#include <iostream>
#include <string>
using namespace std;

int main()
{
    size_t i, j, len;
    string str, str2;

    cout << "Enter string: ";
    getline(cin, str);

    len = str.length();
    str2.reserve(len);

    for(i = 0; i < len; ++i)
    {
        char ch = str[i];
        if (ch != ' ')
            str2 += ch;
    }

    cout << str2 << endl;

    system("pause");
    return 0;
}

Live Demo

Answer 3

This is what worked for me. Thank you everyone for the help!!

int main()
{
int i, j, len;
string str, str2;

cout << "Enter string: ";
getline(cin, str);

len = str.length();

for (i = 0; i < len; ++i)
{
    char ch = str[i];
    if (ch != ' ')
        str2 += ch;
}

cout << str2 << endl;

system("pause");
return 0;
}