stl/map and string question

[drjay1627]

I have string and a map<string,int>

i need to iterate through the map and find string[i] and replace the int with the string.

eg: if map contains

hello 6
world 4
its 3
me 60

if the string is "its me hello world world hello"

output should be "3 60 6 4 4 6"

for(int i = 0 ; i < str.length() ; i++){
         it = mymap.find(str[i]); //it is iterator, mymap is map<string,int> 
          myOutfile << (*it).second; //myOutfile is out stream
        }

i also tried

 for(itStr its = str.begin() ; its < str.end(); its++ ){
            itf = myMap.find(*its);
            myOutfile << (*itf).second;
        }

i get the same error

main.cpp:294: error: invalid conversion from `char' to `const char*'
main.cpp:294: error: initializing argument 1 of `std::basic_str ing<_CharT, _Traits, _Alloc>::basic_ string(const _CharT*, const _Alloc&) [with _CharT = char, _Traits = std::char_trait s<char>, _Alloc = std::allocator< char>]'

can someone please help me fix this!

thanks

drjay

[JosAH]

If Str is a single string I can understand the error message because you're iterating over single characters. Single chars can not be converted to pointers to chars.

kind regards,

Jos

[drjay1627]

what is the way around it?

[Ganon11]

What you are assuming is that your string is treated as an array of words, and that it has an iterator which accesses each word. This isn't what C++ assumes or performs, though. You can work around it by manually parsing your string to get an array/list of words (hint: each word is separated by a space). Put each word into a list or vector, and use that list/vector's iterator, and the code you have will work fine.

[weaknessforcats]

Your loop in incorrectly coded.

You are looking for strings os the loop does not test i < str.length(). Instead test for the number of strings, that is, the number of elements in the string array.

for(unsigned int i = 0 ; i <4 ; i++){ 
etc...

I made this chamge and your code works fine.

[drjay1627]

what if the you dont know the length of the string?

[weaknessforcats]

It's a string object. It knows how long it is.

You can't use a C++ string object using the C-string techniques of C.