array modification in C - c

Question

Not sure what i'm doing wrong here. I'm trying to circularly shift elements of a char array left by one. It seems to work, but not persist. I assume it's a pointer issue, but I still don't get how pointers work so i'm not sure where to begin. Problem is, it only seems to change the value inside the for loop and reset afterwards.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void ip();
int main(){
char d[10] = "010";
char k[10] = "1010000010";
initialPermutation(d, k);
return(0);
}
void ip(char * data, char* key){
int i;
// P10(k1, k2, k3, k4, k5, k6, k7, k8, k9, k10) = (k3, k5, k2, k7, k4, k10, k1, k9, k8, k6)
char P10[10] = {key[2],key[4],key[1],key[6],key[3],key[9],key[0],key[8],key[7],key[6]};
// split P10 into two segments
char left5[5] = {P10[0],P10[1],P10[2],P10[3],P10[4]};
char right5[5] = {P10[5],P10[6],P10[7],P10[8],P10[9]};
// pre shift binary string
printf("Pre-shift: ");
for(i=0;i<5;i++)
printf("%c",left5[i]);
for(i=0;i<5;i++)
printf("%c",right5[i]);
printf("\n");
// circular shift left one bit (here is where the problem is)
for(i=0;i<5;i++){
char templ = left5[4-i];
left5[4-i] = left5[i];
left5[i] = templ;
char tempr = right5[4-i];
right5[4-i] = right5[i];
right5[i] = tempr;
}
printf("Post- (outside for loop): ");
for(i=0;i<5;i++)
printf("%c",left5[i]);
for(i=0;i<5;i++)
printf("%c",right5[i]);
printf("\n");
}

Answer 1

Your loop is not shifting values, it is reversing the array twice.
It swaps index 0 with index 4, then 1 with 3, then 2 with 2, then 3 with 1, and finally 4 with 0. At this point the array is exactly as when you started.
This code does an actual rotary left shift:
char tmp = left5[0];
for(i = 1; i < sizeof(left5); ++i){
left5[i-1] = left5[i]
}
left5[4] = tmp;
If you actually declare the arrays one element too large you can write:
char left5[6] = {P10[0],P10[1],P10[2],P10[3],P10[4]};
left5[5] = left5[0]
for(i=0; i < 5; ++i){
left5[i] = left5[i+1];
}