I would like to submit my enhanced concatenating function for your review. Originally, its' method signature is:

char *concat (const *char1, const *char2); 

but after knowing that the calling code must supply all the arguments when it calls the function, I modified the method signature to:

char *enhconcat (const char *str1, int start_index1, int end_index1, const char *str2, int start_index2, int end_index2); 

supplying the necessary positional arguments, so that the code is, I think more secured and adaptable to future changes.

Please advise on how should the following listing improve, and be more secured.

/* enhconcat.c: enhanced concat - for more secured concatenating */ #include <stdio.h> #include <stdlib.h> #include <string.h> char * enhconcat (const char *str1, int start_index1, int end_index1, const char *str2, int start_index2, int end_index2); int main (void) { const char *part1 = "Cuius est solum, "; const char *part2 = "eius est usque ad coelum et ad inferos."; printf ("%s\n", enhconcat (part1, 0, strlen (part1), part2, 0, strlen (part2))); return (EXIT_SUCCESS); } char * enhconcat (const char *str1, int start_index1, int end_index1, const char *str2, int start_index2, int end_index2) { int m = end_index1 - start_index1; int n = end_index2 - start_index2; char *concatstr; concatstr = malloc (m + n + 1); if (!concatstr) { printf ("Unable to allocate memory.\n"); exit (EXIT_FAILURE); } char *chrptr; chrptr = concatstr; // store address of concatstr for (int i = start_index1; i < m; i++) { *chrptr = str1[i]; chrptr++; } for (int j = start_index2; j < n; j++) { *chrptr = str2[j]; chrptr++; } *chrptr = '\0'; return concatstr; } /* end of enhconcat() */ 

I would like to submit my enhanced concatenating function for your review. Originally, its method signature is:

char *concat (const *char1, const *char2); 

but after knowing that the calling code must supply all the arguments when it calls the function, I modified the method signature to:

char *enhconcat (const char *str1, int start_index1, int end_index1, const char *str2, int start_index2, int end_index2); 

supplying the necessary positional arguments, so I think the code is more secured and adaptable to future changes.

Please suggest ways to improve this code and make it more secure.

/* enhconcat.c: enhanced concat - for more secured concatenating */ #include <stdio.h> #include <stdlib.h> #include <string.h> char * enhconcat (const char *str1, int start_index1, int end_index1, const char *str2, int start_index2, int end_index2); int main (void) { const char *part1 = "Cuius est solum, "; const char *part2 = "eius est usque ad coelum et ad inferos."; printf ("%s\n", enhconcat (part1, 0, strlen (part1), part2, 0, strlen (part2))); return (EXIT_SUCCESS); } char * enhconcat (const char *str1, int start_index1, int end_index1, const char *str2, int start_index2, int end_index2) { int m = end_index1 - start_index1; int n = end_index2 - start_index2; char *concatstr; concatstr = malloc (m + n + 1); if (!concatstr) { printf ("Unable to allocate memory.\n"); exit (EXIT_FAILURE); } char *chrptr; chrptr = concatstr; // store address of concatstr for (int i = start_index1; i < m; i++) { *chrptr = str1[i]; chrptr++; } for (int j = start_index2; j < n; j++) { *chrptr = str2[j]; chrptr++; } *chrptr = '\0'; return concatstr; } /* end of enhconcat() */