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Lesson 9: Strings
This lesson is one on strings. Strings are really arrays, but
there aresome differentfunctions that are used for strings, like
adding to strings, finding the lengthof strings, andalso of
checking to see if strings match. Strings are basically sentences,
or words. Like,"This is a string".
Strings are basically character arrays. For example, to declare
a string of 50 letters, youwould want to say:
char string[50];
This would declare a string with a length of 50 characters.
Don't forget that arrays begin at0, not 1 for the index-number.
Also, a string ends with a null character, literally a
'/0'character. But, just remember that there will be an extra
character on the endon a string. Itis like a period at the end of a
sentence, it is not counted as a letter, but itstill takes up
a space.
What are strings useful for? Well, for one thing, you might want
to get a person's name. If youwanted to, you would need a string,
because a name can't fit in one variable! It is, however,
acollection of characters, and so fits nicely into a character
array.
Now, what if you want to input a string? Well, if you try to use
cin>> then itwon't work! Itterminates at the first space.
However, you can use the function gets(char *s);.
Gets is basically a function that reads in a string and stops
reading at the first new-line, forexample, when a user hits enter.
Gets is in stdio.h. All you do, is put the name of the array and it
will work out,because the pointer char *s is basically one way you
tell a function that you will be passing anarray, although it is a
pointer, it is still the string you give. Essentially,char *s
points toa string, and you can access this string just like an
array.
I will touch upon this relationship as described above in
another lesson that will be a moreadvanced lesson on pointers and
arrays.
Anyway, to get a string from a user you want to use gets. An
example program ofthis would be:
#include //For gets#include //For all other input/output
functions
void main(){
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size_t strlen(const char *s);
strlen will return the length of a string, minus the termating
character(/0). The size_t isnothing to worry about. Just treat it
as an integer.
Some of the stuff in the strings may be confusing. The const
char *s stuff, forexample. But,just remember that basically all of
that will be a string! It doesn't matter what the code isright now,
just what the functions do.
Now, a small program using many of the string functions!
#include //For cout#include //For many of the string
functions#include //For gets
void main(){char name[50]; //Declare variableschar lastname[50];
//This could have been declared on the last line...cout
