Question

I need to define the characters in an array and print the string…But it always prints as string7 (in this case, test7)…What am I doing wrong here?

#include <stdio.h>
int main() {
    char a[]={'t','e','s','t'};
    printf("%s\n",a);
    return 0;
}

Answer 1

Why this behavior?

Because you did not \0 terminate your array, so what you get is Undefined behavior.

What possibly happens behind the scenes ?

The printf tries to print the string till it encounters a \0 and in your case the string was never \0 terminated so it prints randomly till it encounters a \0.
Note that reading beyond the bounds of allocated memory is Undefined behavior so technically this is a UB.

What you need to do to solve the problem?

You need:

char a[]={'t','e','s','t',`\0`};

or

char a[]="test";