Format string, integer with leading zeros

问题:

I Use this code:

NSString* strName = [NSString stringWithFormat:@"img_00%d.jpg", pp];

and works fine, but if pp took the value of 10 for example I wish have img_010.jpg as result, and not img_0010.jpg... how can I format the string??

thanks

回答1:

Use the format string "img_%03d.jpg" to get decimal numbers with three digits and leading zeros.

回答2:

For posterity: this works with decimal numbers.

NSString *nmbrStr = @"0033620340000" ;
NSDecimalNumber *theNum = [[NSDecimalNumber decimalNumberWithString:nmbrStr]decimalNumberByAdding: [NSDecimalNumber one]] ;     
NSString *fmtStr = [NSString stringWithFormat:@"%012.0F",[theNum doubleValue]] ;

Though this information is hard to find, it is actually documented here in the second paragraph under Formatting Basics. Look for the % character.

https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/Strings/Articles/FormatStrings.html