tolower( )

Posted on 2004-11-01
Last Modified: 2011-09-20
Below is how i am using to lower built in method to conver a word to lower cases. But for some reason, it is not working. Why?

================================= CODE ===============================
//convert a string to lower case
std::string toLower(std::string & s){
for(unsigned int i = 0; i < s.length(); i++)
 return s;

//read the file word per word, remove punctuation if any,
//store them into vector words. Duplicates not allowed.
void wc::read(istream &f)
   std::string word;
   int count = 0;

    f.seekg(0, ios::beg);
   f >> word;

   word =  toLower(word);
  if( words.find(word) == words.end()  )
   words[word] = 0; //word is not in map set it count to 0 for the first time.

 words[word]++; //word is there, increment its count.
 count++; //count the number of word stored.

 f >> word;
  if(words.size() == 0){
  std::cout<<"File failed to open\n";
  totalCount = count;
  distinctCount = words.size();


Question by:komlaaa
    LVL 11

    Accepted Solution

    tolower('A') returns 'a' - it does not change the value in-place...

    you should do something like:

    s[i] = tolower(s[i]);

    Author Comment

    What does the error message below mean?

    crux:~/cs450/a2> ls
    BUG_LOG     Makefile*   TIME_LOG    main.o      wc.cpp      wc.h
    MANPAGE     README      main.cpp    non_words   wc.cpp~     wc.o
    crux:~/cs450/a2> make
    g++ main.o wc.o -o wc.out
    make: execvp: g++: Permission denied
    make: *** [wc.out] Error 127
    LVL 45

    Assisted Solution


    gcc (specifically, your user ID) doesn't have permission to access a file.

    Can you post your Makefile?

    LVL 4

    Assisted Solution

    Looks like you don't have permission to run g++

    Check if you're allowed to compile on this computer, that is run the following command:
    g++ main.o wc.o -o wc.out

    if you get "g++: permission denied" the root/admin must fix it for you...

    Author Comment

    Here is some info

    crux:~/achille/a4_1> ls
    BUG_LOG*     Makefile*    README*      bible.txt*   f.out*       file1*       main.cpp*    main1.cpp*   test.out*    wc.h*
    MANPAGE*     Makefile_1*  TIME_LOG*    error*       file*        getopt.c*    main.cppn*   main_1.cpp*  wc.cpp*
    crux:~/achille/a4_1> uname -rs
    SunOS 5.8
    crux:~/achille/a4_1> cat Makefile

    all: cs450words

    cs450words:  wc.o main.o getopt.o
            g++ main.o wc.o getopt.o -o cs450words

    wc.o: wc.cpp wc.h
            g++ -g -Wall -ansi -c wc.cpp

    main.o: main.cpp
            g++ -g -Wall -ansi -c main.cpp

    getop.o: getopt.c
            cc -c getopt.c

            /bin/rm -f cs450words main.o wc.o getopt.o *~

    crux:~/achille/a4_1> make
    g++ -g -Wall -ansi -c wc.cpp
    make: execvp: g++: Permission denied
    make: *** [wc.o] Error 127
    LVL 45

    Expert Comment


    Yep.  Do an "ls -l " on the directory where gcc lives.

    I don't recall which directory is appropriate.  "find / -name g++" should tell you.

    LVL 4

    Expert Comment

    "find / -name g++" should gives you every program with "g++" in the name and takes forever to run on an big HDD

    "which g++" gives you the program and takes milliseconds
    LVL 11

    Expert Comment

    this (getting g++ to work) is all off topic from the original question - a seperate question should really have been opened...


    find / -type f -name 'g++'
    will take some time, but not forever...

    If the system is a Linux system there should be "locate" installed:

    locate g++

    Locate is much faster than "find" as a database of applications should be maintained, and "locate" then just searches through this database...

    On my linux server here gcc/g++ are in /usr/bin

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