Question

/* see if user wants to stop */
if (!strcmp (command, "quit")) break;

What is the use of "!" here??​

Answer 1

Answer:

Here "!" is a logical not operator that returns an integer 0 when two  

strings don't match and returns 1 (or might be some other integer x>0) which

if 2 strings are equal. Since the code compares strings in a *lexicographic* way

i.e. character by character, '!' takes the 0 integer value and evaluates as true

and 1 as false. It then checks whether command is equal to "quit" and if it is

not equal then enter the loop and execute all statements and if it is then skip

the if statement.

Reference:

for more info on:-

logical operators

https://brainly.in/question/10874212

loops

https://brainly.in/question/2359999