Problem with QLineEdit and setText

[Elmo23x]

I have a pice of code that looks like this...

...
QLineEdit *t1;
QString str;
 
t1 = new QLineEdit();
str = "hi to everybody";
 
t1->setText(str);
...

...
QLineEdit *t1;
QString str;

t1 = new QLineEdit();
str = "hi to everybody";

t1->setText(str);
...

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After the execution of "t1->setText(str);" the program breaks with a segmentation fault error.

Probably I am doing something very badly.

Thank you for your help

BTW: the code compiles without any error