C Remove new line from multiline string

Question

Whats the most efficient way of removing a  newline  from a std  string

User · Answer

If its anywhere in the string than you can't do better than O(n).

And the only way is to search for '\n' in the string and erase it.

for(int i=0;i<s.length();i++) if(s[i]=='\n') s.erase(s.begin()+i);

For more newlines than:

int n=0;
for(int i=0;i<s.length();i++){
    if(s[i]=='\n'){
        n++;//we increase the number of newlines we have found so far
    }else{
        s[i-n]=s[i];
    }
}
s.resize(s.length()-n);//to delete only once the last n elements witch are now newlines

It erases all the newlines once.

User · Answer

std  string some str   SOME VAL   if   some str size    gt  0  amp  amp  some str some str length  -1       n       some str resize  some str length  -1      or  removes several newlines at the end   some str resize  some str find last not of L  n   1

User · Answer

Use std  algorithms  This question has some suitably reusable suggestions Remove spaces from std  string in C

User · Answer

s erase std  remove s begin    s end      n    s end

User · Answer

About answer 3 removing only the last  n off string code    if   s empty    amp  amp  s s length  -1       n         s erase s length  -1       Will the if condition not fail if the string is really empty    Is it not better to do    if   s empty          if  s s length  -1       n           s erase s length  -1

User · Answer

If the newline is expected to be at the end of the string  then   if   s empty    amp  amp  s s length  -1       n         s erase s length  -1       If the string can contain many newlines anywhere in the string   std  string  size type i   0  while  i  lt  s length          i   s find   n   i       if  i    std  string npos            break            s erase i

User · Answer

You should use the erase-remove idiom  looking for   n   This will work for any standard sequence container  not just string

User · Answer

The code removes all newlines from the string str   O N  implementation best served without comments on SO and with comments in production   unsigned shift 0  for  unsigned i 0  i lt length str     i       if  str i       n               shift       else          str i-shift    str i           str resize str length   - shift

User · Answer

All these answers seem a bit heavy to me   If you just flat out remove the   n  and move everything else back a spot  you are liable to have some characters slammed together in a weird-looking way  So why not just do the simple  and most efficient  thing  Replace all   n s with spaces   for  int i   0  i  lt  str length   i         if  str i       n           str i                  There may be ways to improve the speed of this at the edges  but it will be way quicker than moving whole chunks of the string around in memory

User · Answer

Here is one for DOS or Unix new line       void chomp  string  amp s                    int pos              if  pos s find   n       string  npos                      s erase pos

User · Answer

Another way to do it in the for loop  void rm nl string  amp s        for  int p   s find   n    p     int  string  npos  p   s find   n        s erase p 1       Usage   string data     naaa nbbb nccc nddd n   rm nl data    cout  lt  lt  data     data   aaabbbcccddd

User · Answer

include  lt algorithm gt   include  lt string gt   std  string str   str erase std  remove str begin    str end      n    str end       The behavior of std  remove may not quite be what you d expect   See an explanation of it here

[c++] C++ Remove new line from multiline string

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