"C Language" extracts substrings

 write a function that extracts a substring from a string. The function prototype is as follows: Int substr (Char dst[], char src[],int start, int len) {} target: from   src  the starting position of the array starts at the position of the  start character backward, copying up to  len  non-nul characters to the &NBSP;DST array. After copying is complete, the,dst  array must end with nul bytes. The return value of the function is the length of the string stored in the  dst  array. Code implementation: #include  <stdio.h> #include  <assert.h>int substr (Char dst[], char  src[], int start, int len) {assert (DST); assert (SRC); int ret = 0;while   (start) {src++; start--;} if  (strlen (src)  < len) {Len = strlen (src);} ret = len;while  (len) {*dst++ = *src++;len--;} *dst =  ' + '; return ret;} Int main () {char *p =  "Bit-tech"; char arr[10];char array[10] = {0};int  ret = substr (arr, p, 4,5);p rintf ("%d\n",  ret);p rintf ("%s\n",  arr); System (" Pause "); return 0;} 

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"C Language" extracts substrings