Custom String class adding char* to it in c++ - c++

Question

I have a problem with my custom string operator += so that if I wanted to add a const char* to my custom string String, then it wouldn't add it, it would just be the String. I can get it to work with other custom String objects but not with c strings.
code in String.cpp
String::String(){
length =0;
capacity = 1024;
myStr = new char[0];
}
String::String (const String& s)
{
length = s.getLength();
myStr = new char[length];
for (unsigned j=0; j < length; j++){
myStr[j] = s[j];
}
}
String::String(char c){
length = 1;
myStr = new char(c);
}
String::String(const char* val){
if(val!= nullptr){
int counter = 0;
while(val[counter]!='\0')counter++; //Find length of the char array
length= counter;
myStr = new char[counter];
for(int i =0;i<counter;i++){
myStr[i]=val[i];
}
}else{
length = 1;
myStr = new char[length];
myStr[0] = '\0';
}
}
ostream& operator<< (std::ostream& os, const String& s)
{
os<<s.myStr;
return os;
}
istream& operator>> (std::istream& is, String& s)
{
char* c = new char[1000];
is >> c;
s = String(c);
delete[] c;
return is;
}
String::~String(){
delete[] myStr;
}
int String::getIndex(char getInd) const {
for(int i = 0;i<length;i++){
if(myStr[i]==getInd){
return i;
}
}
}
unsigned String::getLength() const{
return length;
}
String& String::operator+= (const String& s){
unsigned len = length+s.getLength();
char* str=new char[len];
for(int i = 0;i<length;i++){
str[i]=myStr[i];
}
for(int i = 0;i<s.length;i++){
str[length+1]=s[i];
}
delete myStr;
length = len;
myStr= str;
return *this;
}
String& String::operator+=(const char *c) {
unsigned l =0;
while(c[l] !='\0'){
l++;
}
unsigned len =length+l;//new length of new string
char* str = new char[len];
for(int i = 0;i<getLength();i++) {
str[i] = myStr[i];
}
for(int j = 0; j<l;j++){
str[len+j]=c[j];
}
delete myStr;
length = len;
myStr = str;
return *this;
}
String& String::operator=(const String& s){
if(this == &s){
return *this;
}
delete myStr;
length = s.getLength();
myStr = new char[length];
for(int i = 0;i<length;i++){
myStr[i]=s[i];
}
}
char& String::operator[](unsigned i){
if(i>=length) throw 1;
return myStr[i];
}
char String::operator[] (unsigned j) const
{
if (j >= length) throw 1;
return myStr[j];
}
Code in main.cpp
int main() {
char c[] = {'h','i'}
String add = "iscool";
String str="strworks";
str+=add;
str+=c;
cout<<str<<endl;
return 0;
}
The outcome for this program right now in the console is:
strworks
I am not sure what to change about the const char* c += operator function, i believe this is where the error is. I am also trying to use this string in a getline function but I try getline(file,String& s, ','); there is an error and I would appreciate any tips on how to implement the getline function with my new String class. The String str should be histrworks in the second line of output, however it is blank. I have already re written the logic of the += operator but it doesn't seem to be working. Let me know if there is any more information I need to give out that could assist you guys in finding the problem. The ultimate goal of this program is to read in a file of movie reviews and train an algorithim to find out if the review is positive/negative.