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Home » Tip Bank » C++
Language: C++
Expertise: Beginner
May 26, 1998

String arrays and pointers in C++

Question:
I declared a string array, char *cities[15];, to hold the names of 15 cities. I want to allow the user to enter the 15 cities, but I do not know how to use the string array in my cin statement. How do I get the data into the array?

Answer:
Before using any input statements, you'll need to set aside some memory to store the results. Unfortunately, char *cities[15] won't do the trick.

char *cities[15] declares an array of 15 pointers to characters. This easily translates into an array of string pointers, but you haven't declared the memory for the strings that it points to. Definitely a recipe for trouble!

Perhaps the simplest answer is just to allocate a two-dimensional array of characters:

char cities[15][35];

for (int i = 0; i < 15; i++) {
   cout << "Enter a city: ";
   cin >> cities[i];
}
Here, I declared room for 15 strings, each up to 35 characters long (including the terminator).

This is a simple solution, but it's not ideal. For one thing, even though most strings may be less than 34 characters long, you must be sure than none are more. And for those that are less than 34 characters, you end up wasting a bit of memory. To make better use of memory, you could dynamically allocate memory and use other tricks. But that requires a bit more work.

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