Mad on strcmp and strcpy

Question

I am having trouble with this program. I'm not so familiar with the functions strcpy and strcmp. Can any professionals help me or give me some advice?

Answer 1

As others have stated, choose either C-style strings or C++ std::string.

I highly recommend not creating a separate function for searching the string array because passing arrays to functions is difficult for beginners.

Try something like:

#include <string>
#include <iostream>

#define MAX_NAMES 16

int main(void)
{
  std::string  name_container[MAX_NAMES];
  unsigned int names_in_container = 0;
  while (1)
  {
    std::string name_from_user;
    std::cout << "Enter name: ";
    if (!getline(std::cin, name_from_user))
    {
       break; // Exit from the "while" loop
    }

    // Search the name container for the name.
    unsigned int array_slot = 0;
    bool name_found = false;
    for (array_slot = 0; array_slot < names_in_container; ++array_slot)
    {
      if (name_from_user == name_container[array_slot])
      {
          std::cout << "\nName exists in slot " << array_slot << "\n";
          name_found = true;
      }
    }
    if (!name_found)
    {
      if (array_slot >= MAX_NAMES)
      {
        std::cout << "Name container full, cannot add name.\n";
        break;
      }
      else
      {
        name_container[names_in_container] = name_from_user;
        ++names_in_container;
      }
    }
  }
}

Answer 2

Please recognize that you are comingling C++ string (std::string) and the C library strcpy and strcmp functions. They are two different things. You probably need to look at some of the methods available under the std::string class (.c_str, =, ==),

Here are a few comments, and suggestions,

void search (string sid[], //do you intend to pass a string sid, or an array of srings?
             string name[], //do you intend to pass a string name, or an array of strings?
             int No_of_data_input)
{
    char id[100];
    string input;
    char namename[100];
    //comments ignored/removed

    //these two lines declare the function strcpy
    char * strcpy ( char * namename, const char * name );
    char * strcpy ( char * id, const char * sid );
    //do you intend to copy name and sid instead?
        //do you want: strcpy(namename, name[i].c_str() );
        //do you want: strcpy(id, sid[i].c_str() );
        //if so, you want to do this inside your loop on i, below,

    int sameName=0;
    int j=0;

    cout<<"enter id or name";
    getline(cin,input); //you probably want: cin >> input;

    //do you intend to declare the function strcpy yet again?
    char * strcpy ( char * inputinput, const char * input );
    //or do you intend to copy input to some char[]?
        //you probably want: strcpy( inputinput, input.c_str() );

    //you probably want number of elements in sid[] or name[]?
    for(int i=0;i<4;i++){
        //you probably want sid[i] here
        if ((strcmp(inputinput,id[i])==0) || (strcmp(inputinput,name[i])==0)){
        //you could rewrite this as:
        //if( (input == id[i]) || (input == name[i]) ){
            sameName++;
            j=i;
        } //do us a favor
    } //make the ending braces clearer
    cout<<sameName;

    if (sameName==0)
        cout<<"No student found:  ";
    else if (sameName==1)
        cout<<"student found:  "<<name[j]<<endl<<id[j];
    else if (sameName>1)
        cout<<"More than one student found,please enter id";
}

Do you want (or need) to comingle std::string and strcpy, strcmp?

Editing your code, you might want to just use std::string,

void search (string sid[], //do you intend to pass an array of srings?
             string name[], //do you intend to pass an array of strings?
             int count)
{
    string input;
    int same=0;
    int j=0;

    cout<<"enter id or name";
    cin >> input;

    //you probably want number of elements in sid[] or name[]?
    for(int i=0;i<count;++i){
        if( (input == sid[i]) || (input == name[i]) ){
            ++same;
            j=i;
        }
    }
    cout<<"same: "<<same<<endl;
    if (same==0)
        cout<<"No student found:  "<<endl;
    else if (same==1)
        cout<<"student found:  "<<name[j]<<","<<id[j]<<endl;
    else if (same>1)
        cout<<"More than one student found,please enter id"<<endl;
}

Maybe you could use a vector of strings? Then you could use an iterator on the vector.

You may have more success if you define a student record (containing sid and name), and pass a vector of student records. Then use an iterator over that vector -- read about vector and iterators.