I've almost finished this task but have a little trouble in result. Here's the problem description: Given a vector of strings, please implement the following 2 functions to process and output it:

1. process(): remove strings that contain digits and convert others in upper case

2. output(): print the strings and separate them with comma. Hints:

3. If possible, manipulate the vector elements in place to avoid copying vector.

4. It is encouraged to leverage STL functions/algorithms. Expected Output: ==========================================

   Before: abc, 123, 456, xyz

   After: ABC, XYZ

But my code caused the input is not as expected

before process: abc, 123, 456, xyz,
after process: ABC, XYZ,

Please tell me how to remove the comma in the end of string in both case before/after process

Here's my code:

#include <algorithm> 
#include <cctype> 
#include <iostream> 
#include <vector> 
 

void process(std::vector<std::string>& v)
{
    
    // Remove strings that contain digits
    for(std::string &s : v)
        s.erase(std::remove_if(std::begin(s), std::end(s), 
                           [](unsigned char ch) { return std::isdigit(ch); }), 
            s.end()); 
 
    // Convert other characters into upper case
// std::toupper has several overloads
// template <class charT> charT toupper(charT, const locale&)
// int toupper(int ch)
// So taking its address might be complicated.
// We can use lambda to let compiler found the right overload:
// (In addition, as char might be signed or not, and toupper expects unsigned char value (or EOF))
    for(std::string &s : v)
    {
        std::transform(s.begin(), s.end(), s.begin(), 
        [](unsigned char c){ return std::toupper(c); }); 
    }
    std::cout << '\n';
}

void output(std::vector<std::string>& v) 
{
    for(std::string &str : v)
        if(str != "\0")
            std::cout << str << ", "; 
        
}

int main() 
{ 
    std::vector<std::string> v = { "abc", "123", "456", "xyz" };
    std::cout << "Before: "; output(v);
    process(v);
    std::cout << "After: "; output(v);
    return 0;
} 

CodePudding user response：

Print first element of your vector. Make comma be printed with next elements.

void output(const std::vector<std::string> &v) {
  if (v.empty()) {  // make sure v is not empty or v[0] will cause U.B.
    return;
  }

  std::cout << v[0];                       // 1st element printed
  for (size_t i = 1; i < v.size();   i) {  // loop starts with 2nd element
    std::cout << ", " << v[i];
  }

  std::cout << '\n';
}

CodePudding user response：

Sometimes, good old syntax is a good thing.

void output(std::vector<std::string>& v)  {
    
    // clean array
    size_t n = v.size();
    while(n--) if(v[n] == '\0') v.erase(v.begin()   n);
    
    // print words
    for(size_t i = 0; i < v.size();   i) {
        std::cout << v[i];
        if(i < (v.size() - 1) std::cout << ", "; 
    }
}

another method

void output(std::vector<std::string>& v)  {

    // clean array
    size_t n = v.size();
    while(n--) if(v[n] == '\0') v.erase(v.begin()   n);

    // print words
    size_t max = v.size() - 1;

    for(size_t i = 0; i < max;   i) 
        std::cout << v[i] << ", "; 

    std::cout << v[max];
}