如何從不同的線程訪問數組？

Question

我是新來的C語言。我知道線程是如何工作的，但我覺得我還是沒有得到這個想法指針如何與字符數組，如何填充數組與環...

在終端上的錯誤是如下...

q2.c: In function ‘main’: 
q2.c:18:22: warning: multi-character character constant [-Wmultichar] 
q2.c:23:57: warning: multi-character character constant [-Wmultichar] 
q2.c:23:40: warning: passing argument 2 of ‘strcpy’ makes pointer from integer without a cast [enabled by default] 
In file included from q2.c:4:0: 
/usr/include/string.h:128:14: note: expected ‘const char * __restrict__’ but argument is of type ‘int’ 
q2.c: In function ‘myfunc1’: 
q2.c:61:23: error: invalid type argument of unary ‘*’ (have ‘int’) 
ubuntu@ubuntu-VirtualBox:~/Desktop$ gcc q2.c -lpthread -o hell 
q2.c: In function ‘main’: 
q2.c:18:22: warning: multi-character character constant [-Wmultichar] 
q2.c:23:57: warning: multi-character character constant [-Wmultichar] 
q2.c:23:40: warning: passing argument 2 of ‘strcpy’ makes pointer from integer without a cast [enabled by default] 
In file included from q2.c:4:0: 
/usr/include/string.h:128:14: note: expected ‘const char * __restrict__’ but argument is of type ‘int’ 
q2.c: In function ‘myfunc1’: 
q2.c:61:23: error: invalid type argument of unary ‘*’ (have ‘int’) 

代碼：

#include <stdio.h> 
#include <stdlib.h> 
#include <pthread.h> 
#include <string.h> 

void *myfunc1(void *ptr); 
void *myfunc2(void *ptr); 

pthread_mutex_t lock; 
char name[10]; 
int id[10]; 
int i; 

int main (int argc, char argv[]) 
{ 


     memset(name, 'no' , sizeof(name)); 
     memset(id, 0, sizeof(id)); 
     for(i=0; i<10; i++) 
       { 

             strcpy(&name[i], 'name'); 

        id[i] = i; 
       } 
           //name[10] = '\0'; 

     pthread_t thrd1, thrd2; 
     int thret1, thret2; 
     char *msg1 = "First Thread"; 
     char *msg2 = "Second Thread"; 



       thret2 = pthread_create(&thrd2, NULL, myfunc2, (void *)msg2); 
     thret1 = pthread_create(&thrd1, NULL, myfunc1, (void *)msg1); 


     pthread_join(thrd1, NULL); 
     pthread_join(thrd2, NULL); 

     printf("\nthret1 = %d\n", thret1); 
     printf("\nthret2 = %d\n", thret2); 
     sleep(5); 
     printf("Parent Thread exiting...\n"); 
     exit(1); 

     return 0; 
} 

void *myfunc1(void *ptr){ 

     int i; 
     char *msg = (char *)ptr; 
     printf("\nMsg : %s\n", msg); 

     pthread_mutex_lock(&lock); 
      for(i=0; i<10; i++) 
       { 
        printf("\n %s ", *name[i]); 

       } 

     pthread_mutex_unlock(&lock); 
} 

void *myfunc2(void *ptr){ 

     int i; 
     char *msg = (char *)ptr; 
     printf("Msg : %s\n", msg); 

     pthread_mutex_lock(&lock); 
       for(i=0; i<10; i++) 
       { 

        printf("\n%d ", id[i]); 
       } 
     pthread_mutex_unlock(&lock); 
} 

Answer 1

看起來像是你很混淆了字符串和字符常量。

char name [100]; char c;

始終在「雙引號」中的字符串。一個（單個字符）用單引號括起來。所以，「stackoverflow」是一個字符串，'s'，'t'，'a'，'c'，'k'是字符。

另外，從字符串變量中，使用[]運算符提取單個字符，如下所示。請注意，我不使用'*'運算符。

char name[10] ; 
char c; 
strcpy (name,"stackoverflow"); 
printf ("name is %s",name); 
print ("first character of name is %c", name[0]); 

Answer 2

1. '是指定字符，"被指定字符串。在

   memset(name, 'no' , sizeof(name)); 
   

   您正試圖定義'no'這是c中不允許的。

2. memset用於設置一個存儲塊的一個字符值。您可能需要memcpy或strcpy來初始化名稱。

3. char name[10];定義字符數組，但如果你想這個定義字符串數組，你將需要char name[10][NAME_LEN];代替（字符長度的任何最大值）。這也應該修復strcpy錯誤（不要使用＆符號）。

4. 在myfunc1中，您正在提領角色。將它固定到c字符串的數組將有所幫助，但不需要取消引用它來打印它。