. Is it wrong expressing anger?

Anger does not yield any productive result. Whatever be your status in material life, you just cannot achieve anything with anger. Think over it; you will have come across some managers/ executives/ directors/ officers who keep yapping at everything. Their subordinates will pretend to be very subservient to them, but the moment that person’s back is turned, they gossip about him. Anger will never fetch you respectability. You will become a laughing stock after some time. You lose your prestige; you lose whatever image you try so hard to fabricate.

 The mystic poet Tiruvalluvar declares,
"சினமென்னும் சேர்ந்தாரைக் கொல்லி இனமென்னும்
ஏமப் புனையைச் சுடும்"

the self-destructive emotion called anger wrecks all relations with kith and kin.

But if a situation warrants anger, learn to talk firmly without losing your temper. "ரௌத்ரம் பழகு"

If someone does something wrong, instead of wasting your time or his time by shouting at him for half an hour, you can appeal to his nobility - - ‘You are such a good person. I never expected this from you.’ Then he will respond, instead of reacting. Tiruvalluvar says,

"குணமென்னும் குன்றேறி நின்றார் வெகுளி கணமேனும் காத்தல் அரிது."

 He who has reached the summit of nobility can never retain anger for even a second.