I recently optimized a Linux-C Applet and used the snprintf () function to write data to an array (or string. I don't need sprintf () because it is not safe enough. Accidentally, it will cause memory overflow, resulting in "segment errors "! I have known and used snprintf () for a long time, but today I fully understand the meaning of its return value. Function prototype:
Int snprintf (char * STR, size_t size, const char * format ,...);Size is used to limit the number of bytes (including '\ 0' at the end) written to Str '). Because if the sprintf () function is successful, the number of bytes (number of characters) written to the sprintf () function is returned, and I always thought that the snprintf () function is also like this, that is, snprintf () the function does not return an integer greater than the size. See the following manual:
The functions snprintf () and vsnprintf () do not write more than size bytes (including the trailing '\ 0 '). if the output was truncated due to this limit then the return value is the number of characters (not including the trailing '\ 0') which wowould
Have been written to the final string if enough space had been available. Thus, a return value of size or more means that the output was truncated.If the output is truncated due to the size limit, the returned value is "if there is enough storage space
YingNumber of characters that can be output (excluding '\ 0' at the end of the string) ". The value is equal to or greater than the size! That is to say, if the string that can be written is "0123456789 abcdef" with a total of 16 bits, but the size limit is 10, then the returned value of snprintf () will be
16
Instead of 10! The above content also says that if the returned value is equal to or greater than the size, it indicates that the output string is truncated (truncated ).
Ladies and Gentlemen ~ Note ~
Address: http://snailwarrior.blog.51cto.com/680306/152913
