Thread: Problem argument of type "char" is incompatible with parameter of type "char *"

Hello i am programing arduino but i have a little problem.
so Here is my part of my code:

Code:

void play_game(char *secret)
{
  char **history;
  char *guess;
  int pokus = 0;
  int peg_a;
  int peg_b;
  int Chistory = 0;

  guess[0] = 0;
  guess[1] = 1;
  guess[2] = 2;
  guess[3] = 3;
  char *k = (char *) guess[0];

  turn_off_leds();
  lcd_clear();

  lcd_print_at(1, 2, "Welcome");
  lcd_print_at(1, 2, "Your goal");

  while (true) {
    delay(100);
    if (digitalRead(BTN_ENTER_PIN == HIGH)) {
      break;
    }
  }
  lcd_clear();
  lcd_print_at(0, 1, "I think");
  lcd_print_at(0, 2, "Your ate");
  lcd_print_at(12, 2, k);
  lcd_print_at(13, 2, guess[1]);
  lcd_print_at(14, 2, guess[2]);
  lcd_print_at(15, 2, guess[3]);

  while (true) {
    if (digitalRead(BTN_1_PIN) == HIGH &&
        digitalRead(BTN_2_PIN) == LOW &&
        digitalRead(BTN_3_PIN) == LOW && digitalRead(BTN_4_PIN) == LOW) {
      if (guess[0] == 9) {
        guess[0] = 0;
      } else {
        guess[0]++;
      }
      lcd_print_at(12, 2, (char *) guess[0]);
      lcd_print_at(13, 2, guess[1]);
      lcd_print_at(14, 2, guess[2]);
      lcd_print_at(15, 2, guess[3]);

lcd_print_at is declared:

Code:

      void lcd_print(char *text) {
        Serial.print(text);
        lcd.print(text);
      }

      void lcd_print_at(int y, int x, char *text) {
        lcd_set_cursor(y, x);
        lcd_print(text);
      }

and my error look like this:

Code:

src\master.cpp:178:31: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
     lcd_print_at(1,2,"Welcome");
                               ^
src\master.cpp:179:33: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
     lcd_print_at(1,2,"Your goal");
                                 ^
src\master.cpp:191:30: warning: invalid conversion from 'char' to 'char*' [-fpermissive]
     lcd_print_at(13,2,guess[1]);
                              ^
In file included from src\master.cpp:2:0:
src\lcd_wrapper.h:50:6: note:   initializing argument 3 of 'void lcd_print_at(int, int, char*)'
 void lcd_print_at(int y, int x,char* text);
      ^
src\master.cpp:192:30: warning: invalid conversion from 'char' to 'char*' [-fpermissive]
     lcd_print_at(14,2,guess[2]);
                              ^
In file included from src\master.cpp:2:0:
src\lcd_wrapper.h:50:6: note:   initializing argument 3 of 'void lcd_print_at(int, int, char*)'
 void lcd_print_at(int y, int x,char* text);
      ^
src\master.cpp:193:30: warning: invalid conversion from 'char' to 'char*' [-fpermissive]
     lcd_print_at(15,2,guess[3]);
                              ^
In file included from src\master.cpp:2:0:
src\lcd_wrapper.h:50:6: note:   initializing argument 3 of 'void lcd_print_at(int, int, char*)'
 void lcd_print_at(int y, int x,char* text);
      ^
src\master.cpp:206:45: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
             lcd_print_at(12,2,(char*)guess[0]);
                                             ^
src\master.cpp:207:38: warning: invalid conversion from 'char' to 'char*' [-fpermissive]
             lcd_print_at(13,2,guess[1]);
                                      ^
In file included from src\master.cpp:2:0:
src\lcd_wrapper.h:50:6: note:   initializing argument 3 of 'void lcd_print_at(int, int, char*)'
 void lcd_print_at(int y, int x,char* text);
      ^
src\master.cpp:208:38: warning: invalid conversion from 'char' to 'char*' [-fpermissive]
             lcd_print_at(14,2,guess[2]);
                                      ^
In file included from src\master.cpp:2:0:
src\lcd_wrapper.h:50:6: note:   initializing argument 3 of 'void lcd_print_at(int, int, char*)'
 void lcd_print_at(int y, int x,char* text);
      ^
src\master.cpp:209:38: warning: invalid conversion from 'char' to 'char*' [-fpermissive]
             lcd_print_at(15,2,guess[3]);
                                      ^
In file included from src\master.cpp:2:0:
src\lcd_wrapper.h:50:6: note:   initializing argument 3 of 'void lcd_print_at(int, int, char*)'
 void lcd_print_at(int y, int x,char* text);
      ^
src\master.cpp:223:38: warning: invalid conversion from 'char' to 'char*' [-fpermissive]
             lcd_print_at(12,2,guess[0]);
                                      ^
In file included from src\master.cpp:2:0:
src\lcd_wrapper.h:50:6: note:   initializing argument 3 of 'void lcd_print_at(int, int, char*)'
 void lcd_print_at(int y, int x,char* text);
      ^
src\master.cpp:224:38: warning: invalid conversion from 'char' to 'char*' [-fpermissive]
             lcd_print_at(13,2,guess[1]);
                                      ^
In file included from src\master.cpp:2:0:
src\lcd_wrapper.h:50:6: note:   initializing argument 3 of 'void lcd_print_at(int, int, char*)'
 void lcd_print_at(int y, int x,char* text);
      ^
src\master.cpp:225:38: warning: invalid conversion from 'char' to 'char*' [-fpermissive]
             lcd_print_at(14,2,guess[2]);
                                      ^
In file included from src\master.cpp:2:0:
src\lcd_wrapper.h:50:6: note:   initializing argument 3 of 'void lcd_print_at(int, int, char*)'
 void lcd_print_at(int y, int x,char* text);
      ^
src\master.cpp:226:38: warning: invalid conversion from 'char' to 'char*' [-fpermissive]
             lcd_print_at(15,2,guess[3]);

I dont know what i am doing wrong. Can you help me with my code?

ISO C++ forbids converting a string constant to 'char*'

These warnings are telling you that you passed a string literal as an argument where the parameter is a char* rather than const char*. The reason why this is a red flag is that what a char* parameter points to could be modified, whereas a string literally cannot be safely modified.

In your case, the simple solution is to change the parameter to be a const char* since the function really doesn't modify what the pointer points to.

invalid conversion from 'char' to 'char*'

These warnings are telling you that you passed a char as an argument, but a char* was expected. You need to turn the char into a string, either in the caller, or by overloading the function.

i did something like this

Code:

char **history;

char guess[4];
int pokus = 0;
int peg_a;
int peg_b;
int Chistory = 0;

guess[0] = 0;
guess[1] = 0;
guess[2] = 0;
guess[3] = 0;
guess[4] = '\0';
.... .....lcd_print_at(12, 2, guess[0]);
lcd_print_at(13, 2, guess[1]);
lcd_print_at(14, 2, guess[2]);
....

and error is

Code:

src\master.cpp: In function 'void play_game(char*)':
src\master.cpp:193:30: warning: invalid conversion from 'char' to 'const char*' [-fpermissive]
     lcd_print_at(12,2,guess[0]);
                              ^
In file included from src\master.cpp:2:0:
src\lcd_wrapper.h:50:6: note:   initializing argument 3 of 'void lcd_print_at(int, int, const char*)'
 void lcd_print_at(int y, int x,const char* text);
      ^
src\master.cpp:194:30: warning: invalid conversion from 'char' to 'const char*' [-fpermissive]
     lcd_print_at(13,2,guess[1]);
                              ^
In file included from src\master.cpp:2:0:
src\lcd_wrapper.h:50:6: note:   initializing argument 3 of 'void lcd_print_at(int, int, const char*)'
 void lcd_print_at(int y, int x,const char* text);
      ^
src\master.cpp:195:30: warning: invalid conversion from 'char' to 'const char*' [-fpermissive]
     lcd_print_at(14,2,guess[2]);
                              ^
In file included from src\master.cpp:2:0:
src\lcd_wrapper.h:50:6: note:   initializing argument 3 of 'void lcd_print_at(int, int, const char*)'
 void lcd_print_at(int y, int x,const char* text);
      ^
src\master.cpp:196:30: warning: invalid conversion from 'char' to 'const char*' [-fpermissive]
     lcd_print_at(15,2,guess[3]);

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