Changed C++ to C (#21734)

Changed a reference to C++ to C.

guide/english/c/if-statements/index.md

@@ -68,7 +68,7 @@ There are a few important things that are different here. First, `stdbool.h` has
 Within the parenthesis of the if statement is something new, too: `n == 3`. This is a comparison between `n` and the number 3. `==` is the comparison operator, and is one of several comparison opertations in C.
 
 ## Nested if-else
-The if-else statement allows a choice to be made between two possible alternatives. Sometimes a choice must be made between more than two possibilities. For example the sign function in mathematics returns -1 if the argument is less than zero, returns +1 if the argument is greater than zero and returns zero if the argument is zero. The following C++ statement implements this function:
+The if-else statement allows a choice to be made between two possible alternatives. Sometimes a choice must be made between more than two possibilities. For example the sign function in mathematics returns -1 if the argument is less than zero, returns +1 if the argument is greater than zero and returns zero if the argument is zero. The following C statement implements this function:
 
 ```C
 if (x < 0)