In this lab, we will develop a small utility program that can fix indentation in C or C++ source code files. It will have some limitations, but it will be able to cover a significant subset of valid C++ programs. Specifically, given a file with messed up indentation style:

 int main(){ // Hi, I'm a program! int x = 1; for(int i = 0; i < 10; i++) { cout << i; cout << endl; } } 

It will output a well-formatted program:

int main(){ // Hi, I'm a program! int x = 1; for(int i = 0; i < 10; i++) { cout << i; cout << endl; } } 

Task B. Counting blocks opened and closed by { and }, and adding real indentation

To count open blocks, we need to count how many curly braces get opened and closed on each line, so we need to count { and }

Write a function

int countChar(string line, char c); 

that scans the line and returns the number of occurrences of the character c.

Write a new program indent.cpp that enhances the program from the previous task. As it reads the input line by line, it should also count the number of open and closed { } in it, and keep track of how many blocks is currently open at the beginning of each line.

In the listing below, the number of open blocks is shown on the left:

0 int main(){ 1 // Hi, I'm a program! 1 int x = 1; 1 for(int i = 0; i < 10; i++) { 2 cout << i; 2 cout << endl; 2 } 1 } 

Then instead of printing the number of open blocks, add that number of tabs '\t' at the beginning of each line, and you will get:

int main(){ // Hi, I'm a program! int x = 1; for(int i = 0; i < 10; i++) { cout << i; cout << endl; } // <-- closing for loop } // <-- closing main 

Notice that the closing curly braces are indented one level further than what they should be.

To fix that, when indenting the line, check its very first character. If it is a closing curly brace }, its indentation level should be reduced by one:

int main(){ // Hi, I'm a program! int x = 1; for(int i = 0; i < 10; i++) { cout << i; cout << endl; } } 

Shortcomings of our program:

No support for loops and if statements that dont have curly braces. For example,

if (c == 'A') s = s + c; 

will be incorrectly indented as

if (c == 'A') s = s + c; 

No support for // and /* */. Commented out curly braces should not affect indentation

Symbols {, } inside string and char literals are misinterpreted as blocks

if (true) { s = "{{"; t = "ABC"; } 

will be incorrectly indented as

if (true) { s = "{{"; t = "ABC"; }