Ex1: Copied Code from Intro CPP repo:

git@git.deboone.nl:ericteunis/documenten/uni/m.cpp.git

.gitignore

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+*.out
+*.o
+*.a

ex1/ex1.1/hello_world.cpp

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+#include <iostream>
+using namespace std ;
+
+int main() {
+	cout << "Hello World" << endl ;
+	return 0 ;
+}

ex1/ex1.2/string_analyzer.cpp

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+#include <iostream>
+using namespace std ;
+
+#define MAX_STR_LENGTH 50
+
+int main() {
+
+	char str[MAX_STR_LENGTH];
+	// set pointer to beginning of str
+	char* ptr = &str[0];
+
+	// get string from user
+	std::cout << "Enter string (N < " << MAX_STR_LENGTH << ") :";
+	std::cin.getline (str, MAX_STR_LENGTH);
+	std::cout << std::endl;
+
+	// loop while the pointer does not point to a null byte
+	// move the pointer one position at the end of the loop
+	unsigned int chars_capital = 0, chars_lower = 0, chars_digits = 0, chars_other = 0;
+	while ( *ptr != 0 )
+	{
+		if ( *ptr >= int('A') && *ptr <= int('Z') )
+		{
+			++chars_capital;
+		}
+		else if ( *ptr >= int('a') && *ptr <= int('z') )
+		{
+			++chars_lower;
+		}
+		else if ( *ptr >= int('0') && *ptr <= int('9') )
+		{
+			++chars_digits;
+		}
+		else
+		{
+			++chars_other;
+		}
+
+		// move pointer one char further
+		++ptr;
+	}
+
+	std::cout << chars_capital << " Uppercase" << std::endl;
+	std::cout << chars_lower   << " Lowercase" << std::endl;
+	std::cout << chars_digits  << " Digits"    << std::endl;
+	std::cout << chars_other   << " Other"     << std::endl;
+
+	return 0 ;
+}

ex1/ex1.3/join_strings.cpp

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+#include <iostream>
+#include <string.h>
+
+// join will return a pointer of type 'char'
+char* join(const char*, const char*) ;
+char* joinb(const char*, const char*) ;
+
+
+int main()
+{
+	std::cout << join("alpha","bet") << std::endl ;
+	std::cout << joinb("duck","soup") << std::endl ;
+	
+	return 0 ;
+}
+
+/* this function is owner of new_str,
+ * since it doesn't delete it, there is leakage
+ */
+
+char* join(const char* str1 , const char* str2)
+{
+	/* use 'new' because we don't know how big the strings are going to be
+	 * the length should be 'strlen(str1) + strlen(str2) + 1'
+	 *  since strlen does not count the null bytes we need to add one
+	 */
+
+	int size = strlen(str1) + strlen(str2) + 1;
+
+	char* new_str = new char[size];
+	*new_str =  0; // Null String
+
+	strcat(new_str, str1); // new_str = 0 + str1
+	strcat(new_str, str2); // new_str = new_str + str2
+
+	return new_str;
+
+}
+
+char* joinb(const char* str1 , const char* str2)
+{
+	int size = strlen(str1) + strlen(str2) + 1;
+
+	char* new_str = new char[size];
+	*new_str =  0;
+
+	strcat(new_str, str1);
+	strcat(new_str, " "); // insert space, note it is important to have it as a string => \"
+	strcat(new_str, str2);
+
+	return new_str;
+
+}

ex1/ex1.4/leak_memory.cpp

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+/*
+ * Deliberately leak memory
+ *
+ * Free memory decreases for a second.
+ * However, because the program quits, the kernel frees the used memory
+ *
+ * If run for some time, my swap space would fill, afterwards my computer is brought to a halt.
+ *
+ */
+#include <iostream>
+
+#define K 1000
+#define M K*K
+#define G K*M
+
+#define MEMORY_SIZE_IN_CHARS G
+
+int main() {
+	char* throwaway_ptr = new char[MEMORY_SIZE_IN_CHARS];
+
+	std::cout << "We leaked " << MEMORY_SIZE_IN_CHARS * sizeof " " << " bits" << std::endl;
+
+	return 0;
+}
+	
+

ex1/ex1.5/base32.cpp

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+/*
+ * Print a base10 number in base32
+ *
+ * Using a multiple of bits, arithmetic is done very fast
+ * since cpus talk bits, we can use bit operations which are faster
+ *+ than regular (base10) operations
+ *
+ * also, in base 2^k you can see the splitting on bits
+ * with k the amount of bits used to represent the character
+ * =>
+ * b2: "1100001010100101"
+ * b10: "49829"
+ * ==
+ * b2 per 4 bits: "1100 0010 1010 0101"
+ * b10: "12 2 10 5"
+ * b16: "C  2 A  5"
+ * ==
+ * b2 per 5 bits: "(0000)1 10000 10101 00101"
+ * b10: "1 16 21 5"
+ * b32: "1 G  L  5"
+ */
+
+#include <iostream>
+#include <cmath>
+
+#define VERBOSE false
+
+char b32_lookup_table[] = "ABCDEFGHIJKLMNOPQRSTUV";
+int base = 8;
+
+int main() {
+	//a
+	unsigned int number = 16384;
+	// get the input unsigned integer
+	std::cout << "Enter a Positive Integer: ";
+	std::cin >> number;
+	
+	if ( VERBOSE ) {
+		std::cout << "Number " << number << std::endl;
+		std::cout << "Base " << base << std::endl;
+	}
+
+	//b
+	int bits_in_char = log(base)/log(2);// 5 = log2(32)
+	int bits_in_int = 8 * sizeof(int);// 32 bits
+	
+	int chars_per_int = std::ceil(bits_in_int / bits_in_char);// 7 chars needed
+
+	if ( VERBOSE ) {
+		std::cout << "Chars per int = " << chars_per_int << " ( " << bits_in_int << " / " << bits_in_char << " ) " << std::endl;
+	}
+
+	//c
+	unsigned short digits[chars_per_int];
+
+	//d & e
+	short digit_num = 0;
+	short lsb_bitmask = ( 1 << bits_in_char ) - 1;// 00011111 = 0x1F
+
+	if ( VERBOSE ) {
+		std::cout << "Bitmask = 0x" << std::uppercase << std::hex << lsb_bitmask << std::dec << std::endl;
+		std::cout << std::endl;
+	}
+
+	// Loop until the remainder is 0
+	// I'm truncating all 0s in front of MSB
+	while ( number > 0 )
+	{
+		if ( VERBOSE ) {
+			std::cout << "Entering loop with number = " << number << std::endl;
+			std::cout << " - b16: 0x" << std::hex << number << std::dec << std::endl;
+		}
+		
+		// Mask with the last 5 bits
+		digits[digit_num] = number & lsb_bitmask;
+		
+		// Shift off the bits we have put in to the array
+		number = ( number >> bits_in_char );
+
+		++digit_num;
+	}
+	--digit_num;
+
+	if ( VERBOSE ) {
+		std::cout << "We have " << digit_num + 1 << " digits" << std::endl;
+		std::cout << std::endl;
+	}
+
+
+	//f
+	// Loop the other way so the first digit we get out is MSB
+	while ( digit_num >= 0 ) 
+	{
+		if ( digits[digit_num] < 10 )
+		{
+			std::cout << digits[digit_num];
+		}
+		else 
+		{
+			std::cout << b32_lookup_table[digits[digit_num] - 10];
+		}
+
+		digit_num--;
+	}
+
+	std::cout << std::endl;
+
+	return 0;
+}