diff --git a/project.yml b/project.yml
index cfbdf24..11236c5 100644
--- a/project.yml
+++ b/project.yml
@@ -47,6 +47,7 @@
   :test:
     - *common_defines
     - TEST
+    - UNITY_INCLUDE_DOUBLE
   :test_preprocess:
     - *common_defines
     - TEST
diff --git a/src/inputHandling.c b/src/inputHandling.c
index efa40c9..e202cd7 100644
--- a/src/inputHandling.c
+++ b/src/inputHandling.c
@@ -2,57 +2,89 @@
 #include <string.h>
 #include <stdio.h>
 #include <stdlib.h>
-#define STRINGL 200
 
-char a[STRINGL];
-void deleteWhitespace();
-op readFunction(char* data, int length);
-void getnumbers(char* data, int length, calc_op* structure_ref);
-void printstruct(calc_op* formula);
 
+char formulaBuffer[1000];
+calc_op* resultCalc = NULL;
+calc_op* currentCalc = NULL;
 
-void input() {
-    printf("Geben Sie eine Rechenoperation ein (Bsp.: 1+1):\n");
-    fgets(a, STRINGL, stdin);     //fgets statt scanf, holt den kompletten String inkl. Whitespace
-    deleteWhitespace();
-    calc_op temp;
-    temp.formel = a;
-    temp.funktionstyp = readFunction(a, 10);
-    getnumbers(a,STRINGL, &temp);
-    printstruct(&temp);
+void processInput(char* formStr, int len) {
+    deleteWhitespace(formStr, len);
+    if (resultCalc != NULL){
+        free(resultCalc);
+    }
+    resultCalc = malloc(sizeof(calc_op));
+    memset(resultCalc, 0, sizeof(calc_op));
+    resultCalc->functionsType = opResult;
+    memcpy(formulaBuffer, formStr, len);
+    calc_op * nextCalc = NULL;
+    nextCalc= malloc(sizeof(calc_op));
+    memset(nextCalc, 0, sizeof(calc_op));
+    nextCalc->formular = formStr;
+    nextCalc->parent = (void*) resultCalc;
+    nextCalc->functionsType = detectFunctionOperator(formulaBuffer, 10);
+    if (getNumbers(formulaBuffer, len, nextCalc) == NULL){
+        resultCalc->children[0] = (void*) nextCalc;
+        showStruct(nextCalc);
+    } else {
+        printf("Formular %s not supported", resultCalc->formular);
+    }
+}
+
+calc_op* getNextCalc(){
+    calc_op* newCalc = NULL;
+    if (currentCalc != NULL){
+        newCalc = (calc_op*) currentCalc->parent;
+        if (newCalc == NULL) {
+            return NULL;
+        }
+        newCalc->inputNumbers[0]= currentCalc->result;
+        free(currentCalc);
+    } else {
+        newCalc = (calc_op*) resultCalc->children[0];
+    }
+    if (newCalc==NULL){
+        return NULL;
+    }
+    currentCalc = newCalc; // get ext calculation
+    showStruct(currentCalc);
+    return currentCalc;
 }
 
 //Leerzeichen löschen
-void deleteWhitespace(){
-    for(int i=0; i<STRINGL; i++){
-        if(a[i]==' '){
-            for (int j=i; j<STRINGL; j++){
-           a[j]=a[j+1];
+void deleteWhitespace(char* formStr, int len){
+    for(int stringPos=0; stringPos < len; stringPos++){
+        if((formStr[stringPos] == ' ') || (formStr[stringPos] == '\n') || (formStr[stringPos] == '\r')){
+            for (int j=stringPos; j < len; j++){
+                formStr[j]=formStr[j + 1];
             }
+            stringPos--;
         }
     }
 }
 
 //Einfachste Rechenoperationen lesen
-op readFunction(char* data, int length){
-    for(int i=0; i<length; i++){
-        switch (data[i]){
+op detectFunctionOperator(char* formStr, int len){
+    for(int stringCount=0; stringCount < len; stringCount++){
+        switch (formStr[stringCount]){
             case '+': return opAdd;
             case '-': return opSub;
-            case '/': return opDiv;
+            case '/':case ':': return opDiv;
             case '*': return opMult;
             case '^': return opExp;
+            case '\0': return opEmpty;
         }
     }
     return opNotSupported;
 }
 
 //Zahlen auslesen (+)
-void getnumbers(char* data, int length, calc_op* structure_ref){ //input sind: string, länge vom String, berechnungsstruct
-    char tmp[length];
-    int i = 0;
+char* getNumbers(char* formStr, int len, calc_op* formRef){ //processInput sind: string, länge vom String, berechnungsstruct
+    // char tmp[len];
+    char* splitPnt;
+    int numPos = 0;
     char delimiter;
-    switch (structure_ref->funktionstyp) {
+    switch (formRef->functionsType) {
         case opAdd:
             delimiter = '+';
             break;
@@ -65,21 +97,28 @@ void getnumbers(char* data, int length, calc_op* structure_ref){ //input sind: s
         case opMult:
             delimiter = '*';
             break;
-        default: return;
+        default: return NULL;
     }
-    memcpy(tmp, data, length);     //string kopiert
-    char *token = strtok(tmp, &delimiter); //An der Stelle von dem ersten Plus wird ein NULL (Stringende) gesetzt
+    // memcpy(tmp, formStr, len);     //string kopiert
+    char *token = strtok(formStr, &delimiter); //An der Stelle von dem ersten Plus wird ein NULL (Stringende) gesetzt
     while (token != NULL) {
-        structure_ref->array[i]=atof(token);  // String zu double konvertiert
-        i++;
+        formRef->inputNumbers[numPos] = atof(token);  // String zu double konvertiert
+        numPos++;
+        splitPnt = token;
         token = strtok(NULL, "+"); //Sucht von der letzten Plus-Stelle an weiter
     }
-    structure_ref->arraylength=i; //Länge des Arrays (also zu berechnende Zahlen) gespeichert
+    formRef->arrayLength=numPos; //Länge des Arrays (also zu berechnende Zahlen) gespeichert
+    op type = detectFunctionOperator(splitPnt, strlen(splitPnt) + 1);
+    if (type != opNotSupported && type != opEmpty){
+        return splitPnt;
+    } else {
+        return NULL;
+    }
 }
 
-void printstruct(calc_op* formula){
-    printf("Berechnung: %s", formula->formel);
-    switch (formula->funktionstyp) {
+void showStruct(calc_op* formRef){
+    printf("\nBerechnung: %s\n", formRef->formular);
+    switch (formRef->functionsType) {
         case opAdd:
             printf("Rechenoperation: Addition\n"); break;
         case opSub:
@@ -92,8 +131,8 @@ void printstruct(calc_op* formula){
             printf("Fehler bei Auswahl der Rechenoperationen \n");
     }
     printf("Calculation Variables:\n");
-    for (int i = 0; i < formula->arraylength; ++i) {
-        printf("Array[%i] = %f\n", i, formula->array[i]);
+    for (int arrayCount = 0; arrayCount < formRef->arrayLength; ++arrayCount) {
+        printf("Array[%i] = %f\n", arrayCount, formRef->inputNumbers[arrayCount]);
     }
-    printf("Result: %f", formula->result);
+    printf("Result: %f\n", formRef->result);
 }
\ No newline at end of file
diff --git a/src/inputHandling.h b/src/inputHandling.h
index 676b08d..76b969f 100644
--- a/src/inputHandling.h
+++ b/src/inputHandling.h
@@ -2,20 +2,25 @@
 #define INPUTHANDLING_H
 
 typedef enum{
-    opAdd, opSub, opDiv, opMult, opExp, opLog, opNotSupported
+    opAdd, opSub, opDiv, opMult, opExp, opLog, opEmpty, opNotSupported, opResult
 }op;
 
 typedef struct {
-op funktionstyp;
-char* formel;
-double array[10];
-int arraylength;
-void* child;
-void* parent;
+op functionsType;
+char* formular;
+double inputNumbers[10];
+int arrayLength;
+void* children[10];  // all children structs which depends on this struct
+void* parent;     // the parent struct which this struct depends on
 double result;
 }calc_op;
 
-extern void input();
-
+extern void processInput(char* formStr, int len);
+extern void showStruct(calc_op* formRef);
+extern void deleteWhitespace(char* formStr, int len);
+extern op detectFunctionOperator(char* formStr, int len);
+extern char* getNumbers(char* formStr, int len, calc_op* formRef);
+extern void showStruct(calc_op* formRef);
+extern calc_op* getNextCalc();
 
 #endif // INPUTHANDLING_H
diff --git a/src/main.c b/src/main.c
index 1bca401..0feff4c 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,6 +1,30 @@
 #include "helloWorld.h"
 #include "inputHandling.h"
+#include "outputHandling.h"
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#define STRING_LENGTH 200
+
+char inputBuffer[STRING_LENGTH] = {0};
 
 void main() {
-    input();
+    calc_op *result = NULL;
+    printf("Geben Sie eine Rechenoperation ein (Bsp.: 1+1):\n");
+    fgets(inputBuffer, STRING_LENGTH, stdin);     //fgets statt scanf, holt den kompletten String inkl. Whitespace
+    processInput(inputBuffer, strlen(inputBuffer));
+    do {
+        result = getNextCalc();
+        if (result == NULL) {
+            break;
+        }
+        if (result->functionsType==opResult) {
+            result->result = result->inputNumbers[0];
+            showResult(result);
+            break;
+        }
+        /* Calculation*/
+        result->result = 65478;
+    } while (1);
+    result = getNextCalc();
 }
diff --git a/src/outputHandling.c b/src/outputHandling.c
new file mode 100644
index 0000000..450b72b
--- /dev/null
+++ b/src/outputHandling.c
@@ -0,0 +1,22 @@
+#include <stdio.h>
+#include "outputHandling.h"
+#include "inputHandling.h"
+
+void buildHexString(char* string, int num) {
+    sprintf(string, "0x%X", num);
+}
+
+void buildOctString(char* string, int num) {
+    sprintf(string, "%o", num);
+}
+
+
+void showResult(calc_op* res) {
+    char string[60] = {0};
+    printf("Das Ergebnis ist: %f\n", res->result);
+    printf("Das Ergebnis in dec: %i\n",(int)res->result);
+    buildHexString(string, (int) res->result);
+    printf("Das Ergebnis in buildHexString: 0x%s\n", string); ;
+    buildOctString(string, (int) res->result);
+    printf("Das Ergebnis in buildOctString: %s\n", string); ;
+}
\ No newline at end of file
diff --git a/src/outputHandling.h b/src/outputHandling.h
new file mode 100644
index 0000000..77ff505
--- /dev/null
+++ b/src/outputHandling.h
@@ -0,0 +1,10 @@
+#ifndef OUTPUTHANDLING_H
+#define OUTPUTHANDLING_H
+
+#include "inputHandling.h"
+
+extern void buildHexString(char* string, int num);
+extern void buildOctString(char* string, int num);
+extern void showResult(calc_op* res);
+
+#endif // OUTPUTHANDLING_H
diff --git a/test/test_inputHandling.c b/test/test_inputHandling.c
index 157270f..c8c9665 100644
--- a/test/test_inputHandling.c
+++ b/test/test_inputHandling.c
@@ -3,18 +3,165 @@
 #include "unity.h"
 
 #include "inputHandling.h"
+char halloWelt[]="Hallo Welt";
+char halloWelt2[]="Hallo  Welt";
+char halloWelt3[]="Ha  llo  W el t ";
+char halloWelt4[]="Ha\n\nllo \r W el\r\r t ";
+calc_op formula = {0};
 
 void setUp(void)
 {
+  formula.functionsType = opNotSupported;
 }
 
 void tearDown(void)
 {
 }
 
-void test_inputHandling_NeedToImplement(void)
+void test_inputHandling_deleteOneWhiteSpace(void)
 {
-    TEST_IGNORE_MESSAGE("Need to Implement inputHandling");
+    deleteWhitespace(halloWelt, 10);
+    TEST_ASSERT_EQUAL_STRING("HalloWelt", halloWelt);
 }
 
+void test_inputHandling_deleteTwoWhiteSpaces(void)
+{
+    deleteWhitespace(halloWelt2, 11);
+    TEST_ASSERT_EQUAL_STRING("HalloWelt", halloWelt2);
+}
+
+void test_inputHandling_deleteManyWhiteSpaces(void)
+{
+    deleteWhitespace(halloWelt3, 16);
+    TEST_ASSERT_EQUAL_STRING("HalloWelt", halloWelt3);
+}
+
+void test_inputHandling_deleteAllOtherCharacter(void)
+{
+    deleteWhitespace(halloWelt4, 19);
+    TEST_ASSERT_EQUAL_STRING("HalloWelt", halloWelt4);
+}
+
+void test_inputHandling_findAddFunctionType(void)
+{
+    op type = opNotSupported;
+    type = detectFunctionOperator("4+5", 3);
+    TEST_ASSERT_TRUE(opAdd == type);
+}
+
+void test_inputHandling_findSubFunctionType(void)
+{
+    op type = opNotSupported;
+    type = detectFunctionOperator("4-5", 3);
+    TEST_ASSERT_TRUE(opSub == type);
+}
+
+void test_inputHandling_findMultiFunctionType(void)
+{
+    op type = opNotSupported;
+    type = detectFunctionOperator("4*5", 3);
+    TEST_ASSERT_TRUE(opMult == type);
+}
+
+void test_inputHandling_findDivFunctionType(void)
+{
+    op type = opNotSupported;
+    type = detectFunctionOperator("4/5", 3);
+    TEST_ASSERT_TRUE(opDiv == type);
+    type = opNotSupported;
+    type = detectFunctionOperator("4:5", 3);
+    TEST_ASSERT_TRUE(opDiv == type);
+}
+
+void test_inputHandling_findExpFunctionType(void)
+{
+    op type = opNotSupported;
+    type = detectFunctionOperator("4^5", 3);
+    TEST_ASSERT_TRUE(opExp == type);
+}
+
+void test_inputHandling_findEmptyFunctionType(void)
+{
+    op type = opNotSupported;
+    type = detectFunctionOperator(halloWelt, 10);
+    TEST_ASSERT_TRUE(opEmpty == type);
+}
+
+void test_inputHandling_getNumbersNoFormular(void)
+{
+    char* pnt = NULL;
+    pnt = getNumbers(halloWelt, 10, &formula);
+    TEST_ASSERT_NULL(pnt);
+}
+
+void test_inputHandling_getNumbersAddFormular(void)
+{
+    char* pnt = NULL;
+    char add[] = "4+5";
+    formula.functionsType = detectFunctionOperator(add,3);
+    TEST_ASSERT_TRUE(formula.functionsType == opAdd);
+    pnt = getNumbers(add, 3, &formula);
+    showStruct(&formula);
+    TEST_ASSERT_NULL(pnt);
+    TEST_ASSERT_EQUAL_DOUBLE(4.0, formula.inputNumbers[0]);
+    TEST_ASSERT_EQUAL_DOUBLE(5.0, formula.inputNumbers[1]);
+    TEST_ASSERT_EQUAL_INT(2, formula.arrayLength);
+}
+
+void test_inputHandling_getNumbersSubFormular(void)
+{
+    char* pnt = NULL;
+    char sub[] = "4-5";
+    formula.functionsType = detectFunctionOperator(sub,3);
+    TEST_ASSERT_TRUE(formula.functionsType == opSub);
+    pnt = getNumbers(sub, 3, &formula);
+    showStruct(&formula);
+    TEST_ASSERT_NULL(pnt);
+    TEST_ASSERT_EQUAL_DOUBLE(4.0, formula.inputNumbers[0]);
+    TEST_ASSERT_EQUAL_DOUBLE(5.0, formula.inputNumbers[1]);
+    TEST_ASSERT_EQUAL_INT(2, formula.arrayLength);
+}
+
+void test_inputHandling_getNumbersMultiFormular(void)
+{
+    char* pnt = NULL;
+    char multi[] = "4*5";
+    formula.functionsType = detectFunctionOperator(multi,3);
+    TEST_ASSERT_TRUE(formula.functionsType == opMult);
+    pnt = getNumbers(multi, 3, &formula);
+    showStruct(&formula);
+    TEST_ASSERT_NULL(pnt);
+    TEST_ASSERT_EQUAL_DOUBLE(4.0, formula.inputNumbers[0]);
+    TEST_ASSERT_EQUAL_DOUBLE(5.0, formula.inputNumbers[1]);
+    TEST_ASSERT_EQUAL_INT(2, formula.arrayLength);
+}
+
+void test_inputHandling_getNumbersDivFormular(void)
+{
+    char* pnt = NULL;
+    char div[] = "4/5";
+    formula.functionsType = detectFunctionOperator(div,3);
+    TEST_ASSERT_TRUE(formula.functionsType == opDiv);
+    pnt = getNumbers(div, 3, &formula);
+    showStruct(&formula);
+    TEST_ASSERT_NULL(pnt);
+    TEST_ASSERT_EQUAL_DOUBLE(4.0, formula.inputNumbers[0]);
+    TEST_ASSERT_EQUAL_DOUBLE(5.0, formula.inputNumbers[1]);
+    TEST_ASSERT_EQUAL_INT(2, formula.arrayLength);
+}
+
+void test_inputHandling_getNextCalc(void)
+{
+    calc_op* pnt = NULL;
+    char add[] = "4+5";
+    processInput(add, 3);
+    pnt = getNextCalc();
+    TEST_ASSERT_NOT_NULL(pnt);
+    TEST_ASSERT_TRUE(pnt->functionsType == opAdd);
+    pnt = getNextCalc();
+    TEST_ASSERT_NOT_NULL(pnt);
+    TEST_ASSERT_TRUE(pnt->functionsType == opResult);
+    pnt = getNextCalc();
+    TEST_ASSERT_NULL(pnt);
+}
 #endif // TEST
diff --git a/test/test_outputHandling.c b/test/test_outputHandling.c
new file mode 100644
index 0000000..13b77bb
--- /dev/null
+++ b/test/test_outputHandling.c
@@ -0,0 +1,29 @@
+#ifdef TEST
+
+#include "unity.h"
+
+#include "outputHandling.h"
+
+char string[100]= {0};
+
+void setUp(void)
+{
+}
+
+void tearDown(void)
+{
+}
+
+void test_outputHandling_buildOctString(void)
+{
+    buildOctString(string, 5555555);
+    TEST_ASSERT_EQUAL_STRING("25142543", string);
+}
+
+void test_outputHandling_buildHexString(void)
+{
+    buildHexString(string, 5555555);
+    TEST_ASSERT_EQUAL_STRING("0x54C563", string);
+}
+
+#endif // TEST