錯誤分配使指針從整數開始而沒有強制轉換[默認啟用]

Question

我對C編程很陌生。 我在編譯程序時遇到此錯誤。 我試圖四處尋找解決方案，但無濟於事。 錯誤發生在num = rand()%20;

char* getParameter(char *name)
 {
   char *num;

   char *buffer;


   if(strcmp(name,"Trainingsprogramm")){
    srand (time(NULL));
     num = rand()%20;;
    sprintf(buffer,"%d",num);
}else if(strcmp(name,"Personnenummer")){
     srand (time(NULL));
      num = rand()%20;
    sprintf(buffer,"%d",num);
}else if(strcmp(name,"Tretzustand")){
     srand (time(NULL));
     srand (time(NULL));
      num = rand()%20;
    sprintf(buffer,"%d",num);
}else if(strcmp(name,"Tretleistung")){
     srand (time(NULL));
      num = rand()%20;
    sprintf(buffer,"%d",num);
}else if(strcmp(name,"Drehzahl")){srand (time(NULL));
      num = rand()%20;
    sprintf(buffer,"%d",num);
}else if(strcmp(name,"Geschwindigkeit")){srand (time(NULL));
      num = rand()%20;
    sprintf(buffer,"%d",num);
}else if(strcmp(name,"GefahreneDistanz")){srand (time(NULL));
      num = rand()%20;
    sprintf(buffer,"%d",num);
}else if(strcmp(name,"RealeKJoule")){srand (time(NULL));
      num = rand()%20;
    sprintf(buffer,"%d",num);
}else if(strcmp(name,"AktuellerPuls")){srand (time(NULL));
      num = rand()%20;
    sprintf(buffer,"%d",num);
}else if(strcmp(name,"MomentanerGang")){srand (time(NULL));
      num = rand()%20;
    sprintf(buffer,"%d",num);
}else if(strcmp(name,"RelaxBetrieb")){srand (time(NULL));
      num = rand()%20;
    sprintf(buffer,"%d",num);
}else if(strcmp(name,"VerbrauchteKJoule")){srand (time(NULL));
      num = rand()%20;
    sprintf(buffer,"%d",num);
}

return buffer;

}

Answer 1

嘗試從num的聲明中刪除星形。

char *num; // <<< This is a pointer to char declaration
char num; // <<< This is a char

int num; // <<< But this is probably what you meant/wanted!

Answer 2

賦值使指針從整數...

 char *num;
 ...
 num = rand()%20;

該代碼嘗試將rand()的整數結果分配給字符指針num 。

根據到目前為止顯示的代碼，將num更改為整數，例如

 int num;

可以解決這個問題。

Answer 3

rand()返回一個int ，並且在其上應用%運算符還返回一個int您應將此結果保存為int ，而不是char* ：

int num;
char *buffer;