Solution

/* name: simplestring.cxx
** author: L. Liberti
*/

#include<iostream>
#include<cstring>
#include "simplestring.h"

inline int max(int a, int b) {
  if (a >= b) {
    return a;
  } else {
    return b;
  }
}

SimpleString::SimpleString() : buffer(NULL), theSize(0),
theAllocatedSize(0), theZeroChar('\0') { }

SimpleString::SimpleString(char* initialiseFromArray) {
  using namespace std;
  theSize = strlen(initialiseFromArray);
  int s = max(theSize, theMinimalAllocationSize);
  buffer = new char [s];
  theAllocatedSize = s;
  strcpy(buffer, initialiseFromArray);
}

SimpleString::~SimpleString() {
  if (buffer) {
    delete [] buffer;
  }
}

int SimpleString::size(void) const {
  return theSize;
}

char& SimpleString::operator[](int i) {
  if (i >= theSize || i < 0) {
    return theZeroChar;
  } else {
    return buffer[i];
  }
}

void SimpleString::copyFrom(SimpleString& s) {
  if (buffer) {
    delete [] buffer;
  }
  int ss = s.size();
  int ssalloc = max(ss, theMinimalAllocationSize);
  buffer = new char[ss];
  for(int i = 0; i < ss; i++) {
    buffer[i] = s[i];
  }
  theSize = ss;
}

void SimpleString::append(SimpleString& suffix) {
  int ss = suffix.size();
  if (ss > theAllocatedSize - theSize) {
    // suffix does not fit, reallocate
    char* saveBuffer = buffer;
    int s = theSize + ss + 1;
    buffer = new char [s];
    theAllocatedSize = s;
    strcpy(buffer, saveBuffer);
    delete [] saveBuffer;
  }
  for(int i = 0; i < ss; i++) {
    buffer[i + theSize] = suffix[i];
  }
  theSize = theSize + ss;
  buffer[theSize] = '\0';
}

bool SimpleString::contains(SimpleString& needle) const {
  int s = needle.size();
  bool found;
  for(int i = 0; i < theSize - s; i++) {
    found = true;
    for(int j = i; j < s + i; j++) {
      if (buffer[j] != needle[j - i]) {
        found = false;
        break;
      }
    }
    if (found) {
      break;
    }
  }
  return found;
}

std::ostream& operator<<(std::ostream& out, SimpleString& s) {
  int ss = s.size();
  for(int i = 0; i < ss; i++) {
    out << s[i];
  }
  return out;
}

The makefile is as follows.

all: ssmain

ssmain: ssmain.cxx simplestring.o
	$(CXX) -o ssmain ssmain.cxx simplestring.o

simplestring.o: simplestring.h simplestring.cxx
	$(CXX) -c simplestring.cxx

clean:
	$(RM) -f simplestring.o ssmain