Simulation for strcat and Strncat

Today we simulate the implementation of the two functions strcat and strncat.

First, let's take a look at the strcat function, which means connecting the second string to the end of the first string. Let's take a look at the function prototype: Char *strcat (char *dest, char *src) adds the string src refers to at the end of the dest (overwriting the ' + ' at the end of the dest) and adding '% '. Here's a look at the program:

 #include  <stdio.h> #include  <assert.h>char *my_ strcat  (CHAR&NBSP;*DEST,&NBSP;CHAR&NBSP;*SRC) {Char *ret = dest;assert (dest); assert (SRC); while  (*dest)     //finds the end of the first string through a while loop {dest++;} while  (*dest++ = *src++)   //connects the second string to the first string through this while loop {;} Return ret;} Int main () {char dest[20] =  "Hello";char *psrc =  "world"; char *ret  = my_strcat (DEST,PSRC);p rintf ("%s\n", ret); return 0;} 

    Let's introduce the function of strncat, in fact it is roughly the same as strcat, but it's the difference between "n". Let's look at the function prototype: char *strncat (Char *dest, char *src, int n),   This function is add the first n characters of the string that SRC refers to at the end of the dest (overwrite the ' + ' at the end of the dest) and add '/s '. The difference between this function and the previous one is that the function has a requirement for the number of characters in the second string. So let's take a look at the code:

#include <stdio.h> #include <assert.h>void *my_strncat (char *dest, const char *src,int N) {assert (dest); ASSERT (SRC); while (*dest! = ') {dest++;} while (n--)//through this while loop, the second string of the first n of the Word connect prompt to the first string {*dest++ = *src++;} *dest = ' + ';} int main () {char arr1[10] = "abc"; char arr2[] = "DEFGH"; int num = 0;scanf ("%d", &num); My_strncat (Arr1,arr2,num);p UTS ( ARR1); return 0;}

Through these two pieces of code, I believe that you have been able to understand the difference between the two functions of strcat and Strncat.

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Simulation for strcat and Strncat