use makefile by typing in the command "make" into cmd. Then execute your file like this: ./peepcc [peepfile]
For example: ./peepcc ex1.peep will output out.hml
Peep is a simple, yet powerful, high-level language similar to early versions of the popular language BASIC. Every Peep statement consists of a line number and a Peep instruction. Line numbers must appear in ascending order. Each instruction begins with one of the following Peep commands: rem, input, let, print, goto, if...goto, or end
| Command | Example Statement | Description |
|---|---|---|
rem |
50 rem this is a remark |
Any text following the command rem is for documentation purposes only and is ignored by the compiler. |
input |
30 input x |
Display a question mark prompt to prompt the user to enter an integer. Read that integer from the keyboard and store the integer in x. |
let |
80 let u = 4 * (j - 56) |
Assign u the value of 4 * (j - 56). Note that an arbitrarily complex expression can appear to the right of the equal sign. |
print |
10 print w |
Display the value of w. |
goto |
70 goto 45 |
Transfer control to line 45. |
if/goto |
35 if y == z goto 80 |
Compare y and z for equality and transfer program control to line 80 if the condition is true; otherwise, continue execution with the next statement. |
end |
99 end |
Terminate program execution. |
All commands except end can be used repeatedly. Peep evaluates only integer expressions using the +, -, *, /, and % operators. These operators have the same precedence as in C. Parentheses can be used to change the order of evaluation of an expression.
Peep files should be in lowercase (uppercase letters result in a syntax error unless they appear in a rem statement in which case they are ignored). A variable name is a single letter. Peep does not allow descriptive variable names, so variables should be explained in remarks to indicate their use in the program. Peep uses only integer variables. Peep does not have variable declarations—merely mentioning a variable name in a program causes the variable to be declared and initialized to zero automatically. The syntax of Peep does not allow string manipulation (reading a string, writing a string, comparing strings, etc.). If a string is encountered in a Peep program (after a command other than rem), the compiler generates a syntax error. Our compiler will assume that Peep programs are entered correctly.
Peep uses the conditional if...goto statement and the unconditional goto statement to alter the flow of control during program execution. If the condition in the if...goto statement is true, control is transferred to a specific line of the program. The following relational and equality operators are valid in an if...goto statement: <, >, <=, >=, == or !=. The precedence of these operators is the same as in C.
The first program reads two integers from the keyboard, stores the values in variables a and b, and computes and prints their sum (stored in variable c).
10 rem determine and print the sum of two integers
15 rem
20 rem input the two integers
30 input a
40 input b
50 rem add integers and store result in c
60 let c = a + b
65 rem
70 rem print the result
80 print c
90 rem terminate program execution
99 endHere is another example that determines and prints the larger of two integers. The integers are input from the keyboard and stored in s and t. The if...goto statement tests the condition s >= t. If the condition is true, control is transferred to line 90 and s is output; otherwise, t is output and control is transferred to the end statement in line 99 where the program terminates.
10 rem determin the larger of two integers
20 input s
30 input t
32 rem
35 rem test if s >= t
40 if s >= t goto 90
45 rem
50 rem t is greater than s, so print t
60 print t
70 goto 99
75 rem
80 rem s is greater than or equal to t, so print s
90 print s
99 endPeep does not provide a repetition structure (such as C’s for, while or do...while). However, Peep can simulate each of C’s repetition structures using the if...goto and goto statements. Here is an example of a sentinel-controlled loop to calculate the squares of several integers. Each integer is input from the keyboard and stored in variable j. If the value entered is the sentinel -9999, control is transferred to line 99 where the program terminates. Otherwise, k is assigned the square of j, k is output to the screen and control is passed to line 20 where the next integer is input.
10 rem calculate the squares of several integers
20 input j
23 rem
25 rem test for sentinel value
30 if j == -9999 goto 99
33 rem
35 rem calculate square of j and assign result to k
40 let k = j * j
50 print k
53 rem
55 rem loop to get next j
60 goto 20
99 endThis will take Peep and translate it into HML code.
I decided to do this through 2 ways.