added source files as well as image files required for the project

These files were uploaded into the repository just for completeness.

1191225_program.c

@@ -0,0 +1,304 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <inttypes.h>
+#include <string.h>
+
+#ifdef __cplusplus
+#error *Please use a proper C-Compiler*
+#endif
+
+// needed for reading proper input from stdin
+#define MAX_LINE_LEN 100
+
+#define STUDENT_INFO "Sven", "Vogel", 1191225
+
+// name of the file to write to on --export
+const char *FILE_NAME = "info_export.txt";
+
+/**
+ * @brief read some unsigned int form stdin. The value must be within and including in the range between min and max.
+ * 
+ * @param min minimum value
+ * @param max maximum value
+ * @param msg message
+ * @return unsigned int 
+ */
+unsigned int read_ul(const unsigned int min, const unsigned int max, const char* restrict msg) {
+    // buffer to fit line from stdin
+    char line[MAX_LINE_LEN];
+    // end of buffer
+    char *end = line + MAX_LINE_LEN;
+
+    unsigned int value;
+
+    do {
+        // print message 
+        printf("%s", msg);
+        // flush stdout to make sure every char is written properly
+        fflush(stdout);
+        // read a line from stdin
+        fgets(line, MAX_LINE_LEN, stdin);
+        // parse line to unsigned long
+        value = strtoul(line, &end, 10);
+
+    } while (value > max || value < min);
+
+    return value;
+}
+
+/**
+ * @brief read some double form stdin. The value must be within and including in the range between min and max. 
+ * After each attempt to parse a meaningful value msg will be printed to stdout.
+ * 
+ * @param min minimum value
+ * @param max maximum value
+ * @param msg message
+ * @return unsigned int 
+ */
+double read_lf(const double min, const double max, const char* restrict msg) {
+    // buffer to fit line from stdin
+    char line[MAX_LINE_LEN];
+    // end of buffer
+    char *end = line + MAX_LINE_LEN;
+
+    double value;
+
+    do {
+        // print message 
+        printf("%s", msg);
+        // read a line from stdin
+        fgets(line, MAX_LINE_LEN, stdin);
+        // parse line to double
+        value = strtod(line, &end);
+
+    } while (value > max || value < min);
+
+    return value;
+}
+
+/**
+ * @brief read interest rate and growth rate from stdin
+ * 
+ * @param interestRate 
+ * @param growthRate 
+ * @return true 
+ * @return false 
+ */
+void input_rate_and_growth(double *interestRate, double *growthRate) {
+    
+    // input interest rate
+    *interestRate = read_lf(0.01, 10, "\tEnter interest rate [0.01; 10]: ");
+
+    // input growth rate
+    *growthRate = read_lf(0.01, 5.0, "\tEnter growth rate [0.01; 5]: ");
+}
+
+/**
+ * @brief fill tab with interest calculations. Each row will contain data for the next year.
+ * the columns will contain [0] := interest rate [1] := investment amount [2] := investment growth 
+ * 
+ * @param tab 3 column table
+ * @param duration number of years to calculate for
+ * @param investmentAmount start money
+ * @return double sum off total investments
+ */
+double calculate_interest_growth(double tab[][3], int duration, double investmentAmount) {
+    // declare variables
+    double interestRate;
+    double growthRate;
+    double totalInterests = 0;
+
+    input_rate_and_growth(&interestRate, &growthRate);
+
+    // initialize 1. year
+    tab[0][0] = interestRate;
+    tab[0][1] = investmentAmount;
+    tab[0][2] = investmentAmount * interestRate * 1e-2;
+
+    for(unsigned int year = 1; year < duration; year++) {
+        unsigned int lastYear = year - 1;
+
+        // investment = investment form last year + interest
+        tab[year][1] = tab[lastYear][1] + tab[lastYear][2];
+
+        // interest rate = last interest rate + interest growth
+        tab[year][0] = tab[lastYear][0] + growthRate;
+
+        // interest = investmentAmount * interest rate
+        tab[year][2] = tab[year][1] * tab[year][0] * 1e-2;
+
+        totalInterests += tab[year][2];
+    }
+
+    return totalInterests + tab[0][2];
+}
+
+/**
+ * @brief print the table tab as layouted for calculate_interest_growth() to stdout
+ * 
+ * @param tab 
+ * @param duration number of rows 
+ */
+void output_table(double tab[][3], const unsigned int rows) {
+    printf("\n\tinterest rate [%%] investment [€] annual interest [€]\n");
+
+    unsigned int year = 0;
+
+    // print each row of the table
+    for(unsigned int row = 0; row < rows; row++) {
+        year ++;
+        printf("year %2d:% 12.2lf\t% 12.2lf\t% 10.2lf\n", year, tab[row][0], tab[row][1], tab[row][2]);
+    }
+}
+
+/**
+ * @brief find the maximum value in arr
+ * 
+ * @param arr 
+ * @param len 
+ * @return unsigned int index of the maximum value in arr 
+ */
+unsigned int find_index(double arr[], unsigned int len) {
+    unsigned int current = 0;
+    double max = 0;
+
+    // look through the entire array
+    for (unsigned int x = 0; x < len; x++) {
+        // test if we have found sth bigger than before
+        if (arr[x] > max) {
+            current = x;
+            max = arr[x];
+        }
+    }
+
+    // return index of biggest found element
+    return current;
+}
+
+typedef struct student {
+    const char* name;
+    const char* familyName;
+    // 7-Decimal-Digit UUID number
+    uint32_t matriculationNumber;
+} Student;
+
+/**
+ * @brief create a new stack allocated student
+ * 
+ * @param name forename of the student
+ * @param familyName 
+ * @param matriculationNumber 7-digit unsigned uuid 
+ * @return Student 
+ */
+Student new_student(const char* restrict name, const char* restrict familyName, const uint32_t matriculationNumber) {
+    Student new_stud = {
+        .name = name,
+        .familyName = familyName,
+        .matriculationNumber = matriculationNumber,
+    };
+
+    return new_stud;
+}
+
+/**
+ * @brief writes the format of student to the file specified by FILE_NAME. 
+ * 
+ * @param text 
+ */
+void export_to_disk(const char* restrict text) {
+
+    // open file in write mode only, truncating previous content to zero
+    FILE* handle = fopen(FILE_NAME, "w");
+
+    // file could not be opened
+    if (handle == NULL) {
+        fprintf(stderr, "could not open file to export\n");
+        return;
+    }
+
+    fprintf(handle, "%s", text);
+
+    fclose(handle);
+
+    printf("Author exported to disk. Goodbye!\n");
+}
+
+/**
+ * @brief fill a destination string with the format "Name <NAME>, <FAMILYNAME> Matriekelnummer: <NUMBER>"
+ * 
+ * @param dest string to store in, should be 100 bytes in size
+ * @param author student to take inforamtion from
+ */
+void generate_string(char * restrict dest, const Student *student) {
+    sprintf(dest, "Name: %s %s, Matrikelnummer: %7d\n", student->name, student->familyName, student->matriculationNumber);
+}
+
+int main(int argc, char **argv) {
+
+    const Student author = new_student(STUDENT_INFO);
+
+    unsigned int offerCount;
+    unsigned int years;
+    double investmentAmount;
+
+    char info[100]; // hopefully no one ever has a name longer than 100 chars
+
+    generate_string(info, &author);
+
+    // parse command line argument
+    if (argc > 1 && strcmp(argv[1], "--info") == 0) {
+        printf("%s", info);
+
+        if (argc > 2 && strcmp(argv[2], "--export") == 0) {
+            export_to_disk(info);
+            // abort, were done
+            return 0;
+        }
+    }
+
+    // run for ever. or until the user decides to kill it.
+    while (1) {
+        
+        // input data
+        years = read_ul(1, 50, "Enter investment duration in years [1; 50]: ");
+        investmentAmount = read_lf(100, 10000, "Enter investment amount in € [100; 10000]: ");
+        offerCount = read_ul(1, 3, "Enter offer count [1; 3]: ");
+
+        // allocate table
+        double (*tab)[3] = calloc(years, sizeof(double[3]));
+
+        // allocate array for all offer sums 
+        //  alternative dynamic stack allocation: double totalInterests[offerCount];
+        //  alternative static stack allocation:  double totalInterests[50];
+        double *totalInterests = calloc(offerCount, sizeof(double));
+        
+        for (int i = 0; i < offerCount; i++) {
+            printf("\n--------------------------------------------------------------\n");
+
+            // call berechne_zinswachtum()
+            double totalInterest = calculate_interest_growth(tab, years, investmentAmount);
+
+            // save this offers total interest for later
+            totalInterests[i] = totalInterest;
+
+            output_table(tab, years);
+
+            printf("\nTotal interest after 3 years: %.2lf€\n", totalInterest);
+        }
+
+        // find and print best offer
+
+        unsigned int bestOffer = find_index(totalInterests, offerCount);
+
+        printf("\n--------------------------------------------------------------\n");
+        printf("***Offer %d has the best total interest with %.2lf€ after %d years***\n\n", bestOffer + 1, totalInterests[bestOffer], years);
+        printf("\n--------------------------------------------------------------\n");
+        
+        // free resources
+        free(totalInterests);
+        free(tab);
+    }
+
+    return 0;
+}

README.md

@@ -1,3 +1,29 @@
-# Zinsrechner
+## DHBW interest calculator
 
-Interest calculator source code for the practical project of semester 1
+Program desgin from school. Function and variable names were translated to english.
+
+### Compatability with non ANSI terminal emulators
+
+For the best experience at least an ANSI or UTF-8 compatible terminal is required for special characters such as the € symbol.  
+Please note that a true C-Compiler is required to compile the code. If you don't have one in order to compile with a C++ compiler you may need to remove the macro at the start  
+testing for a C++ compiler and the `restrict` keyword.  
+This program was testet with the following operating systems:
+
+#### Windows 11 Pro (x86\_64)
+
+Tested for Version 10.0.22621 with SDK version 10.0.22000 for Microsoft Visual Studio 17 with MSVC 19.34.31937.
+
+NOTE: Due to cross platform compatability no “safe(r)” functions like `scanf_s` nor any of the `WINAPI` were used. The code should still compile and run without errors or warnings. 
+
+#### Linux (x86\_64)
+
+Tested for Archlinux with vanilla Kernel 6.0.11-arch1-1 and gcc 12.2.0.
+
+### Compile & Run
+
+The code can be freely compiled with any C/C++ compiler like clang, icc, gcc, etc…  
+With the source provided is a  build file for cmake (since this is the default tool I use to compile and test). 
+
+Build with cmake:
+
+`cmake . && cmake --build .`