diff --git a/P04_Modularisieren_von_C_Code/work/modularize/bin/triangle b/P04_Modularisieren_von_C_Code/work/modularize/bin/triangle
new file mode 100755
index 0000000..fddacc5
Binary files /dev/null and b/P04_Modularisieren_von_C_Code/work/modularize/bin/triangle differ
diff --git a/P04_Modularisieren_von_C_Code/work/modularize/src/read.c b/P04_Modularisieren_von_C_Code/work/modularize/src/read.c
index 16187fe..17f07a6 100644
--- a/P04_Modularisieren_von_C_Code/work/modularize/src/read.c
+++ b/P04_Modularisieren_von_C_Code/work/modularize/src/read.c
@@ -12,5 +12,79 @@
  * @brief Lab implementation
  */
 // begin students to add code for task 4.1
+#define EOL 10
+#define PARSE_ERROR -1
+#define READ_ERROR -2
+#define ASCII_SPACE 32
+#define ASCII_DIGIT_0 48
+#define ASCII_DIGIT_9 57
+#define NO_POS -1
+#define BUFFERSIZE 10
+#define EOF -1
+int getInt(int maxResult) {
+    // end of input
+    //int EOF = -1; // end of file
+    //int EOL = 10; // end of line
+    // abnormal return values
+    //int PARSE_ERROR = -1;
+    //int READ_ERROR  = -2;
+    // ASCII Codes
+    //int ASCII_SPACE   = 32; // ' '
+    //int ASCII_DIGIT_0 = 48; // '0'
+    //int ASCII_DIGIT_9 = 57; // '9'
+
+    // conversion buffer
+    //int NO_POS = -1;
+    //int BUFFERSIZE = 10;
+    char buffer[BUFFERSIZE] = {0};
+
+    int result = 0;
+
+    // read line: up to EOL or EOF (i.e. error while reading)
+    int bytes = 0;
+    int input;
+    scanf("%d", &input);
+    while ((input != EOL) && (input != EOF)) { // read whole line
+        if (bytes < BUFFERSIZE) { // only buffer first n characters
+            buffer[bytes] = (char)input;
+            bytes++;
+        } else {
+            result = PARSE_ERROR; // exceed buffer size, continue read line
+        }
+        scanf("%d", &input);
+    }
+    if (input == EOF) {
+        result = READ_ERROR;
+    }
+    // check for numbers: skip leading and trailing spaces
+    // (i.e. this includes all control chars below the space ASCII code)
+    int pos = 0;
+    while((pos < bytes) && (buffer[pos] <= ASCII_SPACE)) pos++; // skip SP
+    int posOfFirstDigit = pos;
+    int posOfLastDigit = NO_POS;
+    while ((pos < bytes)
+           && (buffer[pos] >= ASCII_DIGIT_0)
+           && (buffer[pos] <= ASCII_DIGIT_9))
+    {
+        posOfLastDigit = pos;
+        pos++;
+    }
+    while((pos < bytes) && (buffer[pos] <= ASCII_SPACE)) pos++; // skip SP
+    // produce return value
+    if (result != 0) {
+        // previously detected read or parse error given
+    } else if ((pos != bytes) || (posOfLastDigit == NO_POS)) {
+        result = PARSE_ERROR;
+    } else { // convert number
+        for(int i = posOfFirstDigit; i <= posOfLastDigit; i++) {
+            result = result * 10 + (buffer[i] - ASCII_DIGIT_0);
+            if (result > maxResult) {
+                result = PARSE_ERROR;
+                break;
+            }
+        }
+    }
+    return result;
+}
 
 // end students to add code
diff --git a/P04_Modularisieren_von_C_Code/work/modularize/src/read.d b/P04_Modularisieren_von_C_Code/work/modularize/src/read.d
new file mode 100644
index 0000000..bc19a4f
--- /dev/null
+++ b/P04_Modularisieren_von_C_Code/work/modularize/src/read.d
@@ -0,0 +1 @@
+src/read.o: src/read.c /usr/include/stdc-predef.h
diff --git a/P04_Modularisieren_von_C_Code/work/modularize/src/read.o b/P04_Modularisieren_von_C_Code/work/modularize/src/read.o
new file mode 100644
index 0000000..ec055bf
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diff --git a/P04_Modularisieren_von_C_Code/work/modularize/src/rectang.c b/P04_Modularisieren_von_C_Code/work/modularize/src/rectang.c
index 16187fe..63234fd 100644
--- a/P04_Modularisieren_von_C_Code/work/modularize/src/rectang.c
+++ b/P04_Modularisieren_von_C_Code/work/modularize/src/rectang.c
@@ -12,5 +12,24 @@
  * @brief Lab implementation
  */
 // begin students to add code for task 4.1
+int Rectangular(int a, int b, int c) {
+    int aS = a*a;
+    int bS = b*b;
+    int cS = c*c;
+
+    int isRightAngled;
+    if ((a == 0) && (b == 0) && (c == 0))
+        isRightAngled = 0;
+    else if ((aS + bS) == cS)
+        isRightAngled = 1;
+    else if ((aS + cS) == bS)
+        isRightAngled = 1;
+    else if ((bS + cS) == aS)
+        isRightAngled = 1;
+    else
+        isRightAngled = 0;
+
+    return isRightAngled;
+}
 
 // end students to add code
diff --git a/P04_Modularisieren_von_C_Code/work/modularize/src/rectang.d b/P04_Modularisieren_von_C_Code/work/modularize/src/rectang.d
new file mode 100644
index 0000000..501f89c
--- /dev/null
+++ b/P04_Modularisieren_von_C_Code/work/modularize/src/rectang.d
@@ -0,0 +1 @@
+src/rectang.o: src/rectang.c /usr/include/stdc-predef.h
diff --git a/P04_Modularisieren_von_C_Code/work/modularize/src/rectang.o b/P04_Modularisieren_von_C_Code/work/modularize/src/rectang.o
new file mode 100644
index 0000000..79f4bce
Binary files /dev/null and b/P04_Modularisieren_von_C_Code/work/modularize/src/rectang.o differ
diff --git a/P04_Modularisieren_von_C_Code/work/modularize/src/triangle b/P04_Modularisieren_von_C_Code/work/modularize/src/triangle
new file mode 100755
index 0000000..0b90df3
Binary files /dev/null and b/P04_Modularisieren_von_C_Code/work/modularize/src/triangle differ
diff --git a/P04_Modularisieren_von_C_Code/work/modularize/src/triangle.c b/P04_Modularisieren_von_C_Code/work/modularize/src/triangle.c
index b6a414b..d052da4 100644
--- a/P04_Modularisieren_von_C_Code/work/modularize/src/triangle.c
+++ b/P04_Modularisieren_von_C_Code/work/modularize/src/triangle.c
@@ -15,9 +15,11 @@
 #include <stdlib.h>
 #include "read.h"
 #include "rectang.h"
-
+int getInt(int maxResult);
+int Rectangular(int a, int b, int c);
 /// max side length
 #define MAX_NUMBER 1000
+#define READ_ERROR -2
 
 
 /**
@@ -27,7 +29,53 @@
 int main(void)
 {
 	// begin students to add code for task 4.1
-	
+
+    while (1) {
+        printf("\nDreiecksbestimmung (CTRL-C: Abbruch)\n");
+
+        int word = 0;
+        int a = 0;
+        int b = 0;
+        int c = 0;
+
+        do {
+            printf("Seite a: ");
+            word = getInt(MAX_NUMBER);
+        }
+        while ((word < 0) && (word != READ_ERROR));
+        if (word >= 0)
+            a = word;
+        else
+            break;
+
+        do {
+            printf("Seite b: ");
+            word = getInt(MAX_NUMBER);
+        }
+        while ((word < 0) && (word != READ_ERROR));
+        if (word >= 0)
+            b = word;
+        else
+            break;
+
+        do {
+            printf("Seite c: ");
+            word = getInt(MAX_NUMBER);
+        }
+        while ((word < 0) && (word != READ_ERROR));
+        if (word >= 0)
+            c = word;
+        else
+            break;
+
+        if (Rectangular(a, b, c) == 1)
+            printf("-> Dreieck %d-%d-%d ist rechtwinklig", a, b, c);
+        else
+            printf("-> Dreieck %d-%d-%d ist nicht rechtwinklig", a, b, c);
+        printf("\n");
+    }
+    printf("\n\nbye bye\n");
+
 	// end students to add code
     return EXIT_SUCCESS;
 }
diff --git a/P04_Modularisieren_von_C_Code/work/modularize/src/triangle.d b/P04_Modularisieren_von_C_Code/work/modularize/src/triangle.d
new file mode 100644
index 0000000..48a0788
--- /dev/null
+++ b/P04_Modularisieren_von_C_Code/work/modularize/src/triangle.d
@@ -0,0 +1,23 @@
+src/triangle.o: src/triangle.c /usr/include/stdc-predef.h \
+ /usr/include/stdio.h \
+ /usr/include/x86_64-linux-gnu/bits/libc-header-start.h \
+ /usr/include/features.h /usr/include/x86_64-linux-gnu/sys/cdefs.h \
+ /usr/include/x86_64-linux-gnu/bits/wordsize.h \
+ /usr/include/x86_64-linux-gnu/bits/long-double.h \
+ /usr/include/x86_64-linux-gnu/gnu/stubs.h \
+ /usr/include/x86_64-linux-gnu/gnu/stubs-64.h \
+ /usr/lib/gcc/x86_64-linux-gnu/7/include/stddef.h \
+ /usr/include/x86_64-linux-gnu/bits/types.h \
+ /usr/include/x86_64-linux-gnu/bits/typesizes.h \
+ /usr/include/x86_64-linux-gnu/bits/types/__FILE.h \
+ /usr/include/x86_64-linux-gnu/bits/types/FILE.h \
+ /usr/include/x86_64-linux-gnu/bits/libio.h \
+ /usr/include/x86_64-linux-gnu/bits/_G_config.h \
+ /usr/include/x86_64-linux-gnu/bits/types/__mbstate_t.h \
+ /usr/lib/gcc/x86_64-linux-gnu/7/include/stdarg.h \
+ /usr/include/x86_64-linux-gnu/bits/stdio_lim.h \
+ /usr/include/x86_64-linux-gnu/bits/sys_errlist.h /usr/include/stdlib.h \
+ /usr/include/x86_64-linux-gnu/bits/floatn.h \
+ /usr/include/x86_64-linux-gnu/bits/floatn-common.h \
+ /usr/include/x86_64-linux-gnu/bits/stdlib-float.h src/read.h \
+ src/rectang.h
diff --git a/P04_Modularisieren_von_C_Code/work/modularize/src/triangle.o b/P04_Modularisieren_von_C_Code/work/modularize/src/triangle.o
new file mode 100644
index 0000000..cd8bc91
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diff --git a/P04_Modularisieren_von_C_Code/work/modularize/tests/tests.d b/P04_Modularisieren_von_C_Code/work/modularize/tests/tests.d
new file mode 100644
index 0000000..2abec9a
--- /dev/null
+++ b/P04_Modularisieren_von_C_Code/work/modularize/tests/tests.d
@@ -0,0 +1,40 @@
+tests/tests.o: tests/tests.c /usr/include/stdc-predef.h \
+ /usr/include/stdio.h \
+ /usr/include/x86_64-linux-gnu/bits/libc-header-start.h \
+ /usr/include/features.h /usr/include/x86_64-linux-gnu/sys/cdefs.h \
+ /usr/include/x86_64-linux-gnu/bits/wordsize.h \
+ /usr/include/x86_64-linux-gnu/bits/long-double.h \
+ /usr/include/x86_64-linux-gnu/gnu/stubs.h \
+ /usr/include/x86_64-linux-gnu/gnu/stubs-64.h \
+ /usr/lib/gcc/x86_64-linux-gnu/7/include/stddef.h \
+ /usr/include/x86_64-linux-gnu/bits/types.h \
+ /usr/include/x86_64-linux-gnu/bits/typesizes.h \
+ /usr/include/x86_64-linux-gnu/bits/types/__FILE.h \
+ /usr/include/x86_64-linux-gnu/bits/types/FILE.h \
+ /usr/include/x86_64-linux-gnu/bits/libio.h \
+ /usr/include/x86_64-linux-gnu/bits/_G_config.h \
+ /usr/include/x86_64-linux-gnu/bits/types/__mbstate_t.h \
+ /usr/lib/gcc/x86_64-linux-gnu/7/include/stdarg.h \
+ /usr/include/x86_64-linux-gnu/bits/stdio_lim.h \
+ /usr/include/x86_64-linux-gnu/bits/sys_errlist.h /usr/include/stdlib.h \
+ /usr/include/x86_64-linux-gnu/bits/floatn.h \
+ /usr/include/x86_64-linux-gnu/bits/floatn-common.h \
+ /usr/include/x86_64-linux-gnu/bits/stdlib-float.h \
+ /usr/include/CUnit/Basic.h /usr/include/CUnit/CUnit.h \
+ /usr/include/string.h /usr/include/math.h \
+ /usr/include/x86_64-linux-gnu/bits/math-vector.h \
+ /usr/include/x86_64-linux-gnu/bits/libm-simd-decl-stubs.h \
+ /usr/include/x86_64-linux-gnu/bits/flt-eval-method.h \
+ /usr/include/x86_64-linux-gnu/bits/fp-logb.h \
+ /usr/include/x86_64-linux-gnu/bits/fp-fast.h \
+ /usr/include/x86_64-linux-gnu/bits/mathcalls-helper-functions.h \
+ /usr/include/x86_64-linux-gnu/bits/mathcalls.h \
+ /usr/include/CUnit/CUError.h /usr/include/errno.h \
+ /usr/include/x86_64-linux-gnu/bits/errno.h /usr/include/linux/errno.h \
+ /usr/include/x86_64-linux-gnu/asm/errno.h \
+ /usr/include/asm-generic/errno.h /usr/include/asm-generic/errno-base.h \
+ /usr/include/CUnit/TestDB.h /usr/include/setjmp.h \
+ /usr/include/x86_64-linux-gnu/bits/setjmp.h \
+ /usr/include/x86_64-linux-gnu/bits/types/__sigset_t.h \
+ /usr/include/CUnit/TestRun.h \
+ /home/vagrant/snp/testlib/include/test_utils.h
diff --git a/P04_Modularisieren_von_C_Code/work/modularize/tests/tests.o b/P04_Modularisieren_von_C_Code/work/modularize/tests/tests.o
new file mode 100644
index 0000000..185a1f6
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