My String Function isn't working again

[ProgrammerSoul]

The string function reverse is supposed to the words in a sentence from a file, for example "This is red" to "red is This."

#include <iostream>
#include <string>
#include <fstream>

using namespace std;

int nwords(string);
string reverse (string);

int main()
{
ifstream myfile;
myfile.open("/Users/Soul/Documents/School/CISC/Assignment9/file.txt");
int numwords;
string next;
   getline(myfile,next);
    while(myfile){
        numwords = nwords(next);
        cout <<"Original line: " << next << endl;
        cout <<"Number of words: "<< numwords << endl;
        cout <<"Reverse version:";
        cout << " " <<reverse(next) << endl << endl;
        getline(myfile,next);
    }
    return 0;
}

int nwords(string str){
int nw = 0, nextblank;
nextblank = str.find(" ",0);
while(nextblank>0){
    nw++;
    str = str.substr(nextblank+1);
    nextblank = str.find(" ",0);
}
return nw+1;
}

string reverse (string str) {
string result="", temp;
int ttllen = str.length();
str.insert(ttllen," ");
int nextblank;
nextblank = str.find(" ",0);
while(nextblank>0){
    temp = str.substr(0,nextblank);
    result.insert(0, " ");
    result.insert(0,temp);
    str = str.substr(nextblank+1);
    nextblank = str.find(" ",0);
}
return result;
}

But the output has a habit with removing the last word. For some reason, it works fine when I use cin instead of using a file.

Output:
Last login: Wed Dec 10 16:44:45 on ttys000
/Applications/CodeBlocks.app/Contents/MacOS/cb_console_runner DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:. /Users/Soul/Documents/School/CISC/Assignment9/bin/Debug/Assignment9
Christians-MacBook-Pro:~ Soul$ /Applications/CodeBlocks.app/Contents/MacOS/cb_console_runner DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:. /Users/Soul/Documents/School/CISC/Assignment9/bin/Debug/Assignment9
Original line: This is assignment number 9
Number of words: 5
number assignment is This

Original line: Computer Science is a very detailed discipline
Number of words: 7
detailed very a is Science Computer

Original line: Although there are many classrooms in Ingersoll Hall some of the classrooms are not available
Number of words: 15
not are classrooms the of some Hall Ingersoll in classrooms many are there Although

Original line: The history of the world is a subject that continues to develop everyday
Number of words: 13
develop to continues that subject a is world the of history The

Original line: Birthday parties are fun
Number of words: 4
are parties Birthday

Original line: This course was easy
Number of words: 4
was course This easy

Original line: The president of Brooklyn College is Karen Gould
Number of words: 8
Karen is College Brooklyn of president The

Original line: I know who Daniel Malloy is.
Number of words: 6
Reverse version: is. Malloy Daniel who know I


Process returned 0 (0x0) execution time : 0.022 s
Press ENTER to continue.

Any help is appreciated

[keskiverto]

Lets assume that your file has two lines.

getline(myfile,next); // This reads the first line
while (myfile) { // This is true on first try
  // do something with next, i.e. handle the first line
  getline(myfile,next); // read the second line.
}

The second line is in next, but now the file is at end and the body of the while will not be executed again.

Try:

while (myfile) {
  getline(myfile,next);
  // do something with next
}

[ProgrammerSoul]

I tried the seggustion, but the output is now:

Last login: Wed Dec 10 17:28:08 on ttys000
/Applications/CodeBlocks.app/Contents/MacOS/cb_console_runner DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:. /Users/Soul/Documents/School/CISC/Assignment9/bin/Debug/Assignment9
Christians-MacBook-Pro:~ Soul$ /Applications/CodeBlocks.app/Contents/MacOS/cb_console_runner DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:. /Users/Soul/Documents/School/CISC/Assignment9/bin/Debug/Assignment9
Original line: This is assignment number 9
Number of words: 5
number assignment is This

Original line: Computer Science is a very detailed discipline
Number of words: 7
detailed very a is Science Computer

Original line: Although there are many classrooms in Ingersoll Hall some of the classrooms are not available
Number of words: 15
not are classrooms the of some Hall Ingersoll in classrooms many are there Although

Original line: The history of the world is a subject that continues to develop everyday
Number of words: 13
develop to continues that subject a is world the of history The

Original line: Birthday parties are fun
Number of words: 4
are parties Birthday

Original line: This course was easy
Number of words: 4
was course This easy

Original line: The president of Brooklyn College is Karen Gould
Number of words: 8
Karen is College Brooklyn of president The

Original line: I know who Daniel Malloy is.
Number of words: 6
Reverse version: is. Malloy Daniel who know I

Original line: I know who Daniel Malloy is.
Number of words: 6
Reverse version: is. Malloy Daniel who know I


Process returned 0 (0x0) execution time : 0.036 s
Press ENTER to continue.

Here is the current code

#include <iostream>
#include <string>
#include <fstream>

using namespace std;

int nwords(string);
string reverse (string);

int main()
{
ifstream myfile;
myfile.open("/Users/Soul/Documents/School/CISC/Assignment9/file.txt");
int numwords;
string next;
    while(myfile){
        getline(myfile,next);
        numwords = nwords(next);
        cout <<"Original line: " << next << endl;
        cout <<"Number of words: "<< numwords << endl;
        cout <<"Reverse version:";
        cout << " " <<reverse(next) << endl << endl;
    }
    return 0;
}

int nwords(string str){
int nw = 0, nextblank;
nextblank = str.find(" ",0);
while(nextblank>0){
    nw++;
    str = str.substr(nextblank+1);
    nextblank = str.find(" ",0);
}
return nw+1;
}

string reverse (string str) {
string result="", temp;
int ttllen = str.length();
str.insert(ttllen," ");
int nextblank;
nextblank = str.find(" ",0);
while(nextblank>0){
    temp = str.substr(0,nextblank);
    result.insert(0, " ");
    result.insert(0,temp);
    str = str.substr(nextblank+1);
    nextblank = str.find(" ",0);
}
return result;
}

[keskiverto]

Sorry, I was on irrelevant issue.

Note that string::find

If no matches were found, the function returns string::npos

Therefore, condition on lines 30 and 44 is not so good.

There is string::append for adding to the end.

What if input contains consecutive whitespace?


Consider alternative strategy, where you read one word at a time from std::istringstream

[PCrumley48]

Strange - it works fine on my compiler. . .

[ProgrammerSoul]

Could the problem be that I'm using a MAC?
For me, the last word is always taken out.