how to remove spaces from a string in C++

Question

I used " using namespace std ;" in my entire study in C++,so basically I don't understand something like std::out,please help me out.Let's say I have a code shown below,i want the two string to be the same when I compare them.

    int main(void)
{
    using namespace std;
    char a[10] = "123    ";
    char b[10] = "123";
    if(strcmp(a,b)==0)
    {cout << "same";}
return 0;
}

Answer 1

use regex \\\\s+ to match all space characters and use regex_replace to remove it

#include <iostream>
#include <regex>
#include <string>

int main()
{
   std::string text = "Quick brown fox";
   std::regex spaces("\\s+");

   // construct a string holding the results
   std::string result = std::regex_replace(text, spaces, "");
   std::cout << '\n' << text << '\n';
   std::cout << '\n' << result << '\n';
}

reference : http://en.cppreference.com/w/cpp/regex/regex_replace

Answer 2

如果您使用 std::string 而不是 char 您可以使用 boost 中的截断函数。

Answer 3

Use std::string to do it

std::string a("123     ");
std::string b("123");
a.erase(std::remove_if(a.begin(), a.end(), ::isspace), a.end());
if (a == b)
    std::cout << "Same";

The difference made by using will be

using namespace std;
string a("123     ");
string b("123");
a.erase(remove_if(a.begin(), a.end(), ::isspace), a.end());
if (a == b)
    cout << "Same";

It is generally advised not to use the using namespace std . Don't forget to include <string> and <algorithm> .

EDIT If you still want to do it the C way, use the function from this post

https://stackoverflow.com/a/1726321/2425366

void RemoveSpaces(char * source) {
    char * i = source, * j = source;
    while (*j != 0) {
        *i = *j++;
        if (*i != ' ') i++;
    }
    *i = 0;
}