what does my reversed array add random characters in C - arrays

Question

I wrote code to reverse an array after in C.
I'm using C17. In the code the user is asked to input a word, the word then is put into an array
and then reversed.
The code works for the exception that it adds some random characters and I couldn't figure out why it does that.
Can you help me with that?
Here is my code
#include <stdio.h>
#define MAXLINE 80
void inputtoarray(char input[]); //Take the input from user and put it into an array
void reverseinput(char input1[]);
int main(){
char input[MAXLINE];
inputtoarray(input);
reverseinput(input);
return 0;
}
void inputtoarray(char input[]){
int c; //to hold the indiviual characters before going into the array
//int was used over char because I want to be able to hold EOF
int i; //i is the array counter
//ask the user to type in a word
printf("Please type in a word:\n");
for(i=0; (c=getchar()) != '\n'; ++i){
input[i] = c;
}
}
void reverseinput(char input1[]){
int cinput;
int coutput;
char temp[MAXLINE]; //define a temporary array
//count the number of characters in the array
for (cinput=0; input1[cinput] != '\0'; ++cinput){
}
coutput=cinput;
//the reversing process. Here cinput holds the number of the last character
for (cinput=0; coutput > 0; --coutput, ++cinput ){
temp[coutput] = input1[cinput];
//input1[coutput] = temp[coutput];
//printf("%s", temp);
}
input1 = temp;
printf("%s", input1);
}

Answer 1

The function inputtoarray does not input a string. As a result this loop
for (cinput=0; input1[cinput] != '\0'; ++cinput){
}
within the function reverseinput results in undefined behavior.
The function inputtoarray can look for example the following way
void inputtoarray( char input[], size_t n )
{
int c; //to hold the indiviual characters before going into the array
//int was used over char because I want to be able to hold EOF
size_t i = 0; //i is the array counter
//ask the user to type in a word
printf("Please type in a word:\n");
for ( ; i + 1 < n && ( c = getchar() ) != EOF && c != '\n'; ++i )
{
input[i] = c;
}
input[i] = '\0';
}
and called like
inputtoarray( input, MAXLINE );
Moreover this loop
for (cinput=0; coutput > 0; --coutput, ++cinput ){
temp[coutput] = input1[cinput];
//input1[coutput] = temp[coutput];
//printf("%s", temp);
}
does not set the element temp[0] due to the condition coutput > 0. So the first element of the array temp has an indeterminate value.
And this assignment
input1 = temp;
does not make a sense because it changes the local variable input instead of changing the array pointed to by the pointer (parameter) input.
Without using standard string functions the program can look the following way.
#include <stdio.h>
#define MAXLINE 80
void inputtoarray( char input[], size_t n )
{
int c; //to hold the indiviual characters before going into the array
//int was used over char because I want to be able to hold EOF
size_t i = 0; //i is the array counter
//ask the user to type in a word
printf("Please type in a word:\n");
for ( ; i + 1 < n && ( c = getchar() ) != EOF && c != '\n'; ++i )
{
input[i] = c;
}
input[i] = '\0';
}
void reverseinput( char input[] )
{
size_t n = 0;
while ( input[n] ) ++n;
if ( n != 0 )
{
for ( size_t i = 0; i < --n; i++ )
{
char c = input[i];
input[i] = input[n];
input[n] = c;
}
}
}
int main(void)
{
char input[MAXLINE];
inputtoarray( input, MAXLINE );
reverseinput( input );
puts( input );
return 0;
}
Its output might look like
Please type in a word:
Hello
olleH