error: invalid conversion from 'char' to 'const char*' - c++

Question

I'm trying to convert all the words into capital letters. Here's the header:
#include <string.h>
#include <ctype.h>
using namespace std;
int Mayusculas(char texto)
{
int liCount;
for(liCount=0;liCount<strlen(texto);liCount++)
{
texto[liCount]=toupper(texto[liCount]);
}
}
Here is the definition in main
char Cadena[100];
and here is where I am using it
case 1:
Mayusculas(Cadena);
cout<<Cadena<<endl;
The error message is
error: invalid conversion from 'char' to 'const char*'

Answer 1

First of all, you have to pass the address of the string, so instead of char, you have to use char*, like this in your function:
void Mayusculas(char *text)
{
for(int post = 0; pos < std::strlen(text); pos++)
{
text[post] = (char) toupper(text[pos]);
}
}
Note: The char *text indicated the address of the first character in your string.
The definition in the main function is good, so you can use it like this:
int main() {
// ...
char Cadena[100];
Mayusculas(Cadena);
std::cout << Cadena << std::endl;
return 0;
}
I have also written an example that you can execute and test here.

Answer 2

TL;DR:
Demo using C-style strings
Demo using std::string
Details
Since we're primarily English-speaking, I'll note that it appears that Mayusculas indicates capital letters, and cadena is a series or chain - in this case a C-style string.
As Presented - C-style Strings
int Mayusculas(char texto) should be int Mayusculas(char *texto)
It needs to be a char * since you are working with a C-style string, and not a single character. Otherwise you have nothing to iterate through.
toupper() returns an int, so you should cast, i.e. change
texto[liCount]=toupper(texto[liCount]);
to
texto[liCount] = (char)toupper(texto[liCount]);
The function signature says you're returning an int, but you don't actually return anything. So either change it to return void, or return something. (liCount, maybe?)
Alternative: std::string
But you tagged this question as C++, so why not use std::string instead of C-style strings? They're safer, and easier to work with.
Quoting Pierre from Convert a String In C++ To Upper Case:
#include <algorithm>
#include <string>
std::string str = "Hello World";
std::transform(str.begin(), str.end(),str.begin(), ::toupper);
Or if you still want it in your own function,
#include <algorithm>
#include <string>
#include <iostream>
using namespace std;
string Mayusculas(std::string str)
{
transform(str.begin(), str.end(), str.begin(), ::toupper);
return str;
}
int main()
{
string Cadena = "Hola al Mundo";
cout << Mayusculas(Cadena) << endl;
return 0;
}
That way returns the result as a string. But if you want to modify it in place like your original, you can do this instead. See it work at Ideone.
void Mayusculas(std::string & str) // reference parameter
{
transform(str.begin(), str.end(), str.begin(), ::toupper);
}
int main()
{
string Cadena = "Hola al Mundo";
Mayusculas(Cadena);
cout << Cadena << endl;
return 0;
}

Answer 3

change your code to: as int may not fit into receiver type char
int Mayusculas(char *texto)
{
int liCount;
for(liCount=0;liCount<strlen(texto);liCount++)
{
texto[liCount]= (char) toupper(texto[liCount]);
}
}