Creating a null terminated string in c

If the data read contains more characters than the array can hold, the string will overflow the array. The C library function strcat can be used to concatenate C strings. This function takes two arguments: 1 a pointer to a destination character array that contains a valid C string, and 2 a pointer to a valid C string or string literal.

The destination array must be large enough to hold the combined strings including the null character. If it is not, the array will overflow. In both cases, the string is passed or returned by address. The string class has several constructors that may be called explicitly or implicitly to create a string object.

The data member p is a pointer to contains the address of the first character in a dynamically-allocated array of characters. The data member length contains the length of the string. The data member capacity contains the number of valid characters that may currently be stored in the array. The subscript specified inside the brackets is passed as an argument to the member function, which then returns the character at that position in the string.

As char will very often be used to store a character code, C designers thought of a simpler way than store a number in a char. You could put a letter between simple quotes and the compiler would understand it must store this character code in the char.

As we very often have to work with a bunch of chars of variable length, C designers also choosed a convention for "strings". Just put a code 0 where the text should end.

By the way there is a name for this kind of string representation "zero terminated string" and if you see the two letters sz at the beginning of a variable name it usually means that it's content is a zero terminated string. That also means that if you have a char array that is not zero terminated, you shouldn't call any of these functions as it will likely do something wrong or you must be extra carefull and use functions with a n letter in their name like strncpy.

The biggest problem with this convention is that there is many cases where it's inefficient. One typical exemple: you want to put something at the end of a 0 terminated string. If you had kept the size you could just jump at the end of string, with sz convention, you have to check it char by char.

Other kind of problems occur when dealing with encoded unicode or such. But at the time C was created this convention was very simple and did perfectly the job. That means that what the pointer points to is a constant that should not be modified if you want to modify it you must first copy it , and that is a good thing because it helps to detect many programming errors at compile time.

The terminating null is there to terminate the string. Without it, you need some other method to determine it's length. Preferably you would use some pre-existing technology that handles unicode, or at least understands string encoding i. And a comment: If you're putting this in a program intended to run on an actual computer, you might consider typedef-ing your own "string".

This will encourage your compiler to barf if you ever accidentally try to pass it to a function expecting a C-style string. S : NULL is a macro 1. Don't mix them up. There are dozens of other ways to store strings, but using a library is often better than making your own.

I'm sure we could all come up with plenty of wacky ways of doing strings without null terminators :. Sign up to join this community.

The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. What is a 'Null Terminated String'? Ask Question. Asked 9 years ago. Active 8 years, 11 months ago. Viewed 78k times. Improve this question. Preet Sangha 2 2 silver badges 13 13 bronze badges. Add a comment. Active Oldest Votes.

Note that we have 24 characters of storage here, and the null will take the 25th character. It's common practice to pre-fill and clear a string with nulls to get rid of any garbage. Improve this answer. Charles Salvia 7, 1 1 gold badge 33 33 silver badges 33 33 bronze badges. An array is not a string, and especially not a null-terminated string. It might contain one though, optionally with space to spare at the end. The conversion constructors of CStrBuf provide various ways to produce C strings, but the conversions can fail due to some of the limitations explained above.

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