How to extract particular string from text file using cpp?

Suppose we have abc.txt file which holds 10 strings and I need to extract particular string according to my choice.

abc.txt

• Print Boundary Sum of a Binary Tree
• Reverse a single linked list
• Greedy Strategy to solve major algorithm problems
• Job sequencing problem
• Root to leaf Path Sum
• Exit Point in a Matrix
• Find length of loop in a linked list
• Toppers of Class
• Print All Nodes that don't have Sibling
• Transform to Sum Tree

Eg let I choose 6 then it will show "Exit Point in a Matrix"