num_bytes()
Return the length of a string in number of bytes.
Syntax
Parameter
Parameter | Definition |
|---|---|
string | text string whose final character is NULL |
num_chars | maximum number of characters to count |
Description
The num_bytes() function returns the number of bytes in a string. It differs from length(), which returns the number of characters. Due to international codesets, a single character can be composed of one or more bytes.
This function counts all bytes in a string until it reaches the NULL character "", which causes the function to return the number of bytes it has counted. You can use the optional num_chars parameter to limit the number of characters that the function counts. For example, if num_chars is 20, num_bytes() returns 20 if the string is 20 characters or longer. It returns a number less than 20, however, if num_bytes() finds a NULL character before it counts the twentieth character.
The following example on shows that num_bytes() reads characters but returns bytes. The num_chars parameter has a value of 4, but num_bytes() returns 6. This difference exists because two of the characters are composed of two bytes.
Example
This example shows the num_bytes() function.
# LANG = ja_JP.eucJP
function run_num_bytes(id, str, nchar){
ret = num_bytes(str, nchar);
printf("ID = %d, nchar = %d, return = %d\n", id, nchar, ret);
}
run_num_bytes("1", "", -1);
run_num_bytes("2", "", 0);
run_num_bytes("3", "", 1);
run_num_bytes("4", "a ", -1);
run_num_bytes("5", "a ", 0);
run_num_bytes("6", "a ", 1);
run_num_bytes("7", "a ", 2);
run_num_bytes("8", "¤Ò¤ç¤¼ ", -1);
run_num_bytes("9", "¤Ò¤ç¤¼ ", 0);
run_num_bytes("10", "¤Ò¤ç¤¼ ", 1);
run_num_bytes("11", "¤Ò¤ç¤¼ ", 2);
run_num_bytes("12", "¤Ò¤ç¤¼ ", 3);
run_num_bytes("13", "¤Ò¤ç¤¼ ", 4);
run_num_bytes("14", "¤Ò¤ç¤¼ ", 10);
The preceding example produces the following output:
ID = 1, nchar = -1, return = 0
ID = 2, nchar = 0, return = 0
ID = 3, nchar = 1, return = 0
ID = 4, nchar = -1, return = 2
ID = 5, nchar = 0, return = 0
ID = 6, nchar = 1, return = 1
ID = 7, nchar = 2, return = 2
ID = 8, nchar = -1, return = 8
ID = 9, nchar = 0, return = 0
ID = 10, nchar = 1, return = 1
ID = 11, nchar = 2, return = 2
ID = 12, nchar = 3, return = 3
ID = 13, nchar = 4, return = 4
ID = 14, nchar = 10, return = 8
Related topics