Sizeof () & array name and pointer

In sizeof function compute, the start address of the array and the pointer to the array are different.

#include <stdio.h>int love(char *p){    printf("sizeof(p) is:%d ", sizeof(p));    return 0;}int main(){    char a[100];    char *l = a;    printf("\nsizeof(a) is:%d and sizeof(l) is:%d \n",sizeof(a), sizeof(l));    love(a);}

Result: sizeof (a) is: 100 and sizeof (l) is: 8

Sizeof (P) is: 8

 

Therefore, in some subfunctions, do not expect to obtain the array size by pointing to the pointer to the first address of the array. The following is an occasional error:

int send_osd_message(char* ip_addr, int port, char * message)  {CACHE_PRINT("\n%s line:%d start ...\n", __func__, __LINE__);int socket_descriptor; int iter=0;struct sockaddr_in address;assert(sendlen);memset(&address, 0, sizeof(address));address.sin_family=AF_INET;address.sin_addr.s_addr=inet_addr(ip_addr);address.sin_port=htons(port);socket_descriptor=socket(AF_INET,SOCK_DGRAM,IPPROTO_UDP);sendto(socket_descriptor,message, sizeof(message),0,(struct sockaddr *)&address,sizeof(address));close(socket_descriptor);CACHE_PRINT("\nMessage is sent to osd:%s\n", ip_addr);return 0;}

 

In this case, even if the message points to a larger array, only 8 bytes of data can be sent on 64-bit machines.