Introduction and concrete usage of strcat_s function in C language

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1. Strcat_s is the security function of the system, which is used to concatenate strings and concatenate two strings together.

2. Strcat_s replaces the strcat function, which can avoid the problem of program crash.

The original strcat function has no way to guarantee a valid buffer size, so it can only assume that the buffer is large enough to cause the program to crash.

Example

# include "stdafx.h" # include # include int main () {_ CrtSetReportMode (_ CRT_ERROR, 0); char str1 [] = "Hello,"; char str2 [] = "world"; int num = strlen (str1) + strlen (str2) + 1; errno_t rlt = strcat_s (str1, num, str2); if (rlt = 0) std::cout