Allocating dinamicaly memory problems and VLA with characters - c

Question

I know I should not use c and c++ at the same time.
Can someone say why the above code are working using new?
the purpose is to remove the central character of an word given by keyboard ex: "abcde" to "abde"
I was asking if the creation of VLA is correct or not... apparently it returns what I want BUT the same main code without the other functions crashes.
I searched throw internet and i discovered that i should initialize the size ('n' in my case)of the VLA's.
Code using functions and new:
#include <stdio.h>
#include <string.h>
int citirea_sirului(char *s1, char *s2)
{
int d;
printf("Cuvantul: ");
gets(s1);
d=strlen(s1);
for(int i=0;i<d;i+=1)
{
*(s2+i)=*(s1+i);
}
return d;
}
void prelucrarea_afis_siruluiC(char *b, int d, char *a){
strcpy(a,b+(d/2)+1);
strcpy(b+(d/2),"");
strcat(b,a);
puts(b);
}
int main(){
int n;
char *cuv,*ccuv;
cuv=new char[n];
ccuv=new char[n];
n=citirea_sirului(cuv,ccuv);
printf("Dimensiunea Cuvantului: %d\n",n);
printf("\nSir prelucrat: \n");
prelucrarea_afis_siruluiC(ccuv,n,cuv);
delete[] ccuv;
delete[] cuv;
return 0;
}
Code without functions:
#include <stdio.h>
#include <string.h>
int main(){
int n;
char cuv[n], ccuv[n];
printf("Cuvantul: ");
gets(cuv);
n=strlen(cuv);
printf("Dimensiunea Cuvantului: %d",n);
for(int i=0;i<n;i++)
{
ccuv[i]=cuv[i];
}
strcpy(cuv,cuv+(n/2)+1);
strcpy(ccuv+(n/2),"");
strcat(ccuv,cuv);
printf("\nCuvantul prelucrat: %s",ccuv);
return 0;
}