how can i write common slot for buttons

i have 121buttons on a gridlayout. On button click i have to connect to a slot.(common to all 121buttons). This worked for me when i used connect function in a for loop.

Code:

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for(i=0;i<121;i++)
    connect(buttons[i],SIGNAL(clicked()),this,SLOT(drawline()));

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But i need the button no in the slot "drawline", I mean in drawline i have to get an integer value. between 1 to 121 corresponding to the button clicked.

I tryed

Code:

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for(i=0;i<121;i++)
    connect(buttons[i],SIGNAL(clicked()),this,SLOT(drawline(i)));

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but doesnot worked

QSignalMapper

it worked