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strcpy / strcmp implementation

 In C/C++ we have a library function called strcpy to copy the source character array to the destination character array. The C++ function details have been documented here. Today I tried to implement it in my own way. I have put forth a few conditions to implement this function, which are described below.

1. I don't want to pass the size of arrays as function parameters. I mean, the parameter gets passed implicitly
2. I don't want the program shall compile if any of the array sizes or both array sizes are zero or one.
3. There shall be no operation if source and destination arrays are the same.
4. No overflow happens if the destination array size is smaller than the source.
5. The destination array must be null-terminated after a successful copy.


Below is the client code to test the implementation:
int main()
{
// Case 1: Source and destination arrays are of the same size
char src[] = "Hello World";
char dest[12] = {}; // n - 1 chars will be copied and the last one will be '\0'

_strcpy(dest, src);
std::cout << "After the copy: " << dest << "\n";

for (int i = 0; i < 12; ++i) {
if (dest[i] == '\0') {
std::cout << "Null termination present..." << "\n";
}
}

// Case 2: Source and destination arrays are of different sizes, destination array size is smaller
char dest_1[6] = {};
_strcpy(dest_1, src);
std::cout << "After the copy: " << dest_1 << "\n";

for (int i = 0; i < 6; ++i) {
if (dest_1[i] == '\0') {
std::cout << "Null termination present..." << "\n";
}
}

// Case 3: source and destination arrays are of different sizes, 
// destination array size is the smallest permissible size...
char dest_2[2] = {};
_strcpy(dest_2, src);
std::cout << "After the copy: " << dest_2 << "\n";

for (int i = 0; i < 2; ++i) {
if (dest_1[i] == '\0') {
std::cout << "Null termination present..." << "\n";
}
}

// Case 4: Src to Src copy, results in no operation just return;
_strcpy(src, src);

// Case 5: The destination array size is bigger than the source array size
char dest_10[100] = {};
_strcpy(dest_10, src);
std::cout << "After the copy: " << dest_10 << "\n";

for (int i = 0; i < 100; ++i) {
if (dest_1[i] == '\0') {
std::cout << "Null termination present..." << "\n";
break;
}
}

// Case 6: Logical error case, source and destination interchanged while calling the API
char dest_11[12] = {};
_strcpy(src, dest_11);
        // Destination to source copy hence src is a null-terminated empty array
std::cout << "After the copy: " << src << "\n"; 
for (int i = 0; i < 12; ++i) {
if (dest_1[i] == '\0') {
std::cout << "Null termination present..." << "\n";
break;
}
}

// Error cases, the program will not compile for the following cases...
/*char dest_3[0] = {};
_strcpy(dest_3, src);

char dest_4[1] = {};
_strcpy(dest_4, src);*/

return 0;
}

A similar way implemented strcmp as below:




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