We often count the system's Memory information on the Linux system regularly to sort out some other problems. In Linux, we can use the following ways to view the system situation:

(1)free -m

(2)cat /proc/meminfo

We can count this information regularly in the program, so we can use the following ways:

Method 1: This method is relatively simple, but it has shortcomings. The field order of each system is different, and there may be some errors.

//proc/meminfo file structure  
//MemTotal:       515164 kB  
//MemFree:         15024 kB  
//Buffers:         13740 kB  
//Cached:         248824 kB  

typedef struct MEMPACKED         
{  
char name1[20];       
unsigned long MemTotal;  
char name2[20];  
unsigned long MemFree;  
char name3[20];  
unsigned long Buffers;  
char name4[20];  
unsigned long Cached;  

}MEM_OCCUPY;  

int  get_meminfo(MEM_OCCUPY * lpMemory)
{
  FILE *fd;
  char buff[128];
  fd = fopen("/proc/meminfo", "r"); 
  if(fd <0) return -1;
  fgets(buff, sizeof(buff), fd); 
  sscanf(buff, "%s %lu ", lpMemory->name1, &lpMemory->MemTotal); 
  fgets(buff, sizeof(buff), fd); 
  sscanf(buff, "%s %lu ", lpMemory->name2, &lpMemory->MemFree);  
  fgets(buff, sizeof(buff), fd);
  sscanf(buff, "%s %lu ", lpMemory->name3, &lpMemory->Buffers);  
  fgets(buff, sizeof(buff), fd);
  sscanf(buff, "%s %lu ", lpMemory->name4, &lpMemory->Cached); 
  
  fclose(fd);	
}

Method 2: This method is very general, completely C method, and easy to understand.

typedef struct MEMPACKED         
{  
char name1[20];       
unsigned long MemTotal;  
char name2[20];  
unsigned long MemFree;  
char name3[20];  
unsigned long Buffers;  
char name4[20];  
unsigned long Cached;  

}MEM_OCCUPY; 

typedef struct os_line_data
{
	char * val;
	int    len;
} os_line_data;

static char * os_getline(char *sin, os_line_data * line, char delim)
{
	char *out = sin;
	if (*out == '\0') return NULL;
//	while (*out && (*out == delim)) { out++; }
	line->val = out;
	while (*out && (*out != delim)) { out++; }
	line->len = out - line->val;
//	while (*out && (*out == delim)) { out++; }
	if (*out && (*out == delim)) { out++; }
	if (*out == '\0') return NULL;
	return out;
}
int Parser_EnvInfo(char * buffer,int size ,MEM_OCCUPY * lpMemory)
{
	int    state = 0;
	char * p     = buffer;
    	while (p)
	{
		os_line_data       line = { 0 };
		p = os_getline(p, &line, ':');
		if (p == NULL || line.len <= 0) continue;
		
		if (line.len == 8&& strncmp(line.val, "MemTotal", 8) == 0)
		{	
			char *point = strtok(p," ");
			memcpy(lpMemory->name1,"MemTotal",8);
                        lpMemory->MemTotal = atol(point);
				
		}
		else if(line.len == 7&& strncmp(line.val, "MemFree", 7) == 0)
		{
			char *point = strtok(p," ");
                        memcpy(lpMemory->name2,"MemFree",7);
                        lpMemory->MemFree = atol(point);
		}
		else if(line.len == 7&& strncmp(line.val, "Buffers", 7) == 0)
		{
			char *point = strtok(p," ");
                        memcpy(lpMemory->name3,"Buffers",7);
                        lpMemory->Buffers = atol(point);
		}
		else if(line.len == 6&& strncmp(line.val, "Cached", 6) == 0)
		{
			char *point = strtok(p," ");
                        memcpy(lpMemory->name4,"Cached",6);
                        lpMemory->Cached = atol(point);
		}
		
	} 	
}

int  get_procmeminfo(MEM_OCCUPY * lpMemory)
{
  FILE *fd;
  char buff[128]={0};
  fd = fopen("/proc/meminfo", "r"); 
  if(fd <0) return -1;
  fgets(buff, sizeof(buff), fd); 
  Parser_EnvInfo(buff,sizeof(buff),lpMemory);
  
  fgets(buff, sizeof(buff), fd);  
  Parser_EnvInfo(buff,sizeof(buff),lpMemory);
  
   fgets(buff, sizeof(buff), fd);  
  Parser_EnvInfo(buff,sizeof(buff),lpMemory);
  
  fgets(buff, sizeof(buff), fd);  
  Parser_EnvInfo(buff,sizeof(buff),lpMemory);
  
  fclose(fd);
	
}
 

In general, we do not advocate using system to make script calls to get these information, especially in embedded environment.