How do I get the memory usage?

[ForestPoem]

my Function.

fp = fopen("/proc/meminfo", "r");

memory usage=(memory total - memory free )*100

Currently this is in use.

However, this seems to be the wrong way.

How do I get the memory usage? in linux

[jsulm]

What exactly do you want to have? Bytes used? Percentage used?
What do you try to calculate with this code: (memory total - memory free )*100 ?
memory total - memory free gives you amount of used kBytes.

[jsulm]

To calculate the percentage of used memory do: (used memory * 100) / memory total

[Charby]

@ForestPoem I am afraid Qt is not proposing a portable solution for this...but could you please detail why you think reading proc/meminfo is the wrong way ?

Another method on linux is reading the sysinfo struct

[ForestPoem]

@ForestPoem

i'm solved.
((total - free + buffer + cache) / total) * 100

[jsulm]

@ForestPoem Are you sure? It should be ((total - free + buffer - cache) / total) * 100
At least cache should not be considered as used memory as it is available for application/system as soon as it is needed. The system just uses unused memory as file cache, but that does not mean that this memory is not available.

[ForestPoem]

@jsulm

How, then, would be appropriate?

i want Utilization.

[jsulm]

Well it depends on what you mean if you say "utilization". From application point of view file cache is free memory.
See here: http://www.logicmonitor.com/blog/2014/07/17/the-right-way-to-monitor-virtual-memory-on-linux/