How do I change the extension of a lot of files?

[prateekrc3]

Suppose I have a large number of files in a directory with the .txt extension.

How can I change the extension of all these to .c?

I KNOW THAT ' ren *.txt *.c ' works from command promt but it did't work from power shell and for terminal.

please help!

[rski]

for i in *.txt; do mv $i  `echo "$i" | sed 's/\.txt$/.c/g'`; done;

[vakula]

ls -1 *.txt | nawk '{p=$0;gsub("txt","c");system("mv "p" "$0);}'

taken from <link removed>

[liamtosurvive]

doesn't work for "mv *txt *.c"?