complete grade calcuator

.idea/artifacts/resources.xml

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+<component name="ArtifactManager">
+  <artifact build-on-make="true" name="resources">
+    <output-path>$PROJECT_DIR$/out</output-path>
+    <root id="root">
+      <element id="dir-copy" path="$PROJECT_DIR$/res" />
+    </root>
+  </artifact>
+</component>

README.md

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+# Term Project Part I
+
+## Three Programs
+
+Create a program (or programs) which show how the language you picked (Kotlin) works with the following:
+
+1. I/O
+1. Data Structures
+1. Control Structures
+
+## Report Card Generator
+

res/sample.grades

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+advanced calculus of one variable: 61
+advanced calculus of one variable: 59
+programming languages: 89
+programming languages: 74
+parallel and distributed computing: 90
+parallel and distributed computing: 71
+programming languages: 96
+programming languages: 92
+programming languages: 95
+parallel and distributed computing: 97
+parallel and distributed computing: 89
+advanced calculus of one variable: 82
+advanced calculus of one variable: 74
+software architecture: 53
+software architecture: 82
+programming languages: 61
+programming languages: 93
+parallel and distributed computing: 91
+parallel and distributed computing: 81
+software architecture: 57
+advanced calculus of one variable: 85
+programming languages: 99
+programming languages: 89
+differential equations: 59
+differential equations: 97
+software architecture: 56
+parallel and distributed computing: 89
+parallel and distributed computing: 66
+differential equations: 58
+software architecture: 98
+software architecture: 66
+advanced calculus of one variable: 79
+differential equations: 53
+advanced calculus of one variable: 96
+parallel and distributed computing: 100
+differential equations: 57
+differential equations: 70
+differential equations: 59
+parallel and distributed computing: 93
+advanced calculus of one variable: 71
+advanced calculus of one variable: 99
+differential equations: 100
+differential equations: 74
+software architecture: 93
+advanced calculus of one variable: 93
+differential equations: 86
+programming languages: 61
+software architecture: 79
+software architecture: 76
+software architecture: 99

src/three_feature.kt

@@ -1,11 +1,48 @@
-import java.util.*
+import java.io.File
+
 
 fun main(args: Array<String>) {
-    val in1 = readLine() ?: ""
+    // File I/O is easily done with `File()` constructor
+    val file = File("res/sample.grades")
 
-    val reader = Scanner(System.`in`)
+    // Maps and Lists are, by default, immutable.
-    val in2 = reader.nextInt()
+    // Specify our data structure to be mutable at both levels
+    val courses = mutableMapOf<String, MutableList<Int>>()
 
-    println(in1)
+    // File supports line iteration with forEachLine, which accepts a code block.
-    print(in2)
+    // `it` is the iteration variable in the code block
+    file.forEachLine {
+        // It is possible to unpack iterables into multiple variables
+        // This is very brittle, though, if improperly formatted
+        val (rawCourse, rawGrade) = it.split(":")
+
+        val course = rawCourse.trim()
+        val grade = rawGrade.trim().toInt()  // string conversion is easy with helper methods like `toInt()` and `toIntOrNull()`
+
+        // collection testing is easy with `in` and `!in` operators
+        if (course !in courses)
+            courses[course] = mutableListOf()  // implicit type arguments are passed: `mutableListOf<Int>()`
+
+        // use `!!` to assert the hash lookup will not be null. We just added it to the map.
+        courses[course]!!.add(grade)
+    }
+
+
+    // Iteration over maps is easy when combined with iterable unpacking
+    for ((course, grades) in courses) {
+        val average = grades.average()  // List<Int> has helper methods such as `sum()` and `average()`
+
+        // use a `when` block as an alternative to case. Supports rich pattern matching,
+        // but we just use it here to check which grade range we're in
+        val letter = when {
+            average > 90 -> "A"
+            average > 80 -> "B"
+            average > 70 -> "C"
+            average > 70 -> "D"
+            else -> "F"
+        }
+
+        // input and output from console are as easy as `println()` and `readline()`
+        println("$course:\n\t$letter ($average)\n")
+    }
 }