I just wrote the following C++ function to programatically determine how much RAM a system has installed. It works, but it seems to me that there should be a simpler way to do this. Can someone tell me if I'm missing something?
getRAM()
{
FILE* stream = popen( "head -n1 /proc/meminfo", "r" );
std::ostringstream output;
int bufsize = 128;
while( !feof( stream ) && !ferror( stream ))
{
char buf[bufsize];
int bytesRead = fread( buf, 1, bufsize, stream );
output.write( buf, bytesRead );
}
std::string result = output.str();
std::string label, ram;
std::istringstream iss(result);
iss >> label;
iss >> ram;
return ram;
}
First, I'm using popen("head -n1 /proc/meminfo")
to get the first line of the meminfo file from the system. The output of that command looks like
MemTotal: 775280 kB
Once I've got that output in an istringstream
, it's simple to tokenize it to get at the information I want. My question is, is there a simpler way to read in the output of this command? Is there a standard C++ library call to read in the amount of system RAM?
On Linux, you can use the function sysinfo
which sets values in the following struct:
#include <sys/sysinfo.h>
int sysinfo(struct sysinfo *info);
struct sysinfo {
long uptime; /* Seconds since boot */
unsigned long loads[3]; /* 1, 5, and 15 minute load averages */
unsigned long totalram; /* Total usable main memory size */
unsigned long freeram; /* Available memory size */
unsigned long sharedram; /* Amount of shared memory */
unsigned long bufferram; /* Memory used by buffers */
unsigned long totalswap; /* Total swap space size */
unsigned long freeswap; /* swap space still available */
unsigned short procs; /* Number of current processes */
unsigned long totalhigh; /* Total high memory size */
unsigned long freehigh; /* Available high memory size */
unsigned int mem_unit; /* Memory unit size in bytes */
char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding for libc5 */
};
If you want to do it solely using functions of C++ (i would stick to sysinfo
), i recommend taking a C++ approach using std::ifstream
and std::string
:
unsigned long get_mem_total() {
std::string token;
std::ifstream file("/proc/meminfo");
while(file >> token) {
if(token == "MemTotal:") {
unsigned long mem;
if(file >> mem) {
return mem;
} else {
return 0;
}
}
// ignore rest of the line
file.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
}
return 0; // nothing found
}