diff --git a/src/userinput.c b/src/userinput.c
index 9792e50..554b296 100644
--- a/src/userinput.c
+++ b/src/userinput.c
@@ -5,6 +5,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <math.h>
+#include <stdbool.h>
 
 void trimLeft(char *input) {
     size_t length = strlen(input);
@@ -79,4 +80,74 @@ void printlf(long double value) {
     else {
         printf("%Lf", value);
     }
+}
+
+long double getNumber(char *message, long double *min, long double *max, long double *greaterThan, long double *smallerThan, long double leftBorder, long double rightBorder) {
+    while (1) {
+        char *input = getstr(message, NULL, NULL);
+        if (strlen(input) == 0) {
+            printf("%s\n", "Fehlende Eingabe!");
+            fflush(stdout);
+            free(input);
+            continue;
+        }
+        char *endptr;
+        long double number = strtold(input, &endptr);
+        if (strlen(endptr) > 0) {
+            printf("%s\n", "Ungueltige Eingabe! Gib eine gueltige Zahl ein.");
+            fflush(stdout);
+            free(input);
+            continue;
+        }
+        free(input);
+        bool isValid = true;
+        if (min != NULL && number < *min) {
+            isValid = false;
+        }
+        if (max != NULL && number > *max) {
+            isValid = false;
+        }
+        if (greaterThan != NULL && !(number > *greaterThan)) {
+            isValid = false;
+        }
+        if (smallerThan != NULL && !(number < *smallerThan)) {
+            isValid = false;
+        }
+        if (number < leftBorder) {
+            isValid = false;
+        }
+        if (number > rightBorder) {
+            isValid = false;
+        }
+        if (isValid) {
+            return number;
+        }
+        printf("Ungueltige Eingabe! Fuer die eingegebene Zahl muss gelten:");
+        if (min != NULL) {
+            printf(" >=");
+            printlf(*min);
+        }
+        if (max != NULL) {
+            printf(" <=");
+            printlf(*max);
+        }
+        if (greaterThan != NULL) {
+            printf(" >");
+            printlf(*greaterThan);
+        }
+        if (smallerThan != NULL) {
+            printf(" <");
+            printlf(*smallerThan);
+        }
+        if (min == NULL && greaterThan == NULL) {
+            printf(" >=");
+            printlf(leftBorder);
+        }
+        if (max == NULL && smallerThan == NULL) {
+            printf(" <=");
+            printlf(rightBorder);
+        }
+        printf("\n");
+        fflush(stdout);
+    }
 }
\ No newline at end of file