Append null character to string c

A string constant such as "some text" is a null-terminated string. So it is an array of characters, with a null character at the end. A string constant is not allowed to have an actual line break in it. But if you write two or more string constants in a row, they are automatically combined into a single string constant.

Combination of consecutive strings only works for string constants, not for other expressions that represent strings. So it takes time that is proportional to the length of the string. Avoid computing strlen s over and over for the same string s in the same function. Function strcmp compares strings s and t for alphabetical ordering or for equality. Alphabetical ordering is determined by character codes. Since 'Z' is 90 and 'a' is 97, Z comes before a in the alphabetical ordering used by strcmp.

Be careful. It adds b to the end of the string in array a. So what is in array a is changed. Also, there must be enough room to add b to a. Strcat will not allocate more room. Below is the implementation of the above approach: C. Previous Strings in C. Recommended Articles. Check if frequency of character in one string is a factor or multiple of frequency of same character in other string. Count of index pairs i, j such that string after deleting ith character is equal to string after deleting jth character.

Append a digit in the end to make the number equal to the length of the remaining string. Find a string such that every character is lexicographically greater than its immediate next character. Last remaining character after repeated removal of the first character and flipping of characters of a Binary String.

Map every character of one string to another such that all occurrences are mapped to the same character. Kth character after replacing each character of String by its frequency exactly X times.

Modify the string such that every character gets replaced with the next character in the keyboard. Count substrings having frequency of a character exceeding that of another character in a string. Following is an ill-formed code and shouldn't be practiced:. At minimum the destination array could be initialized as empty string only the NULL character and after that strcat can be used:.

If the destination character array is declared at global scope, then all elements of the array are initialized to 0 automatically by C. Since a 0 is equivalent to NULL character, an array declared globally can be directly passed to strcat :. Character pointers can be used in strcat :. In the example above, ps points to the 5th character of src and pd points to the 7th character of dest.

Copying starts from the 5th character of src , this is what ps is pointing to. At the end a NULL character is appended. Warning: When using character pointers, care must be taken so that the source and destination aren't overlapped. Following is an example of ill-formed code which uses strcat of overlapped buffer - which causes undefined behaviour:. The strncat function is used to append at most n characters from source string to destination string.

Here is an example:. The example above will append first 4 characters from src at the end of dest i. Warning: The destination character array must be large enough to hold all characters of destination, n characters of source and a NULL character.