Question

strptime_l is always returning null. I’m doing this in Objective-C.

#import <time.h>
#import <xlocale.h>

/* Later on... */      

    const char *str = [dateStr UTF8String];
    const char *fmt = [@"EE LLLL d HH:mm:ss Z yyyy" UTF8String];
    struct tm timeinfo;
    memset(&timeinfo, 0, sizeof(timeinfo));
    char *ret = strptime_l(str, fmt, &timeinfo, NULL);

    NSDate *date = nil;

    if (ret) {
        time_t time = mktime(&timeinfo);

        date = [NSDate dateWithTimeIntervalSince1970:time];
    }

ret is always null. An example of dateStr‘s value is: Sat Sep 15 05:52:10 +0000 2012 and is always in that format.

Any ideas?

Answer 1

You seem to be using the NSDateFormatter format instead of the strptime one. Take a look here for more info its specific date and time format.

The following code should work:

NSString *dateStr = @"Sat Sep 15 05:52:10 +0000 2012";

const char *str = [dateStr UTF8String];
const char *fmt = [@"%a %b %d %H:%M:%S %z %Y" UTF8String];
struct tm timeinfo;
memset(&timeinfo, 0, sizeof(timeinfo));
char *ret = strptime_l(str, fmt, &timeinfo, NULL);

NSDate *date = nil;

if (ret) {
    time_t time = mktime(&timeinfo);

    date = [NSDate dateWithTimeIntervalSince1970:time];
}

By the way you could have achieved the same by simply doing:

NSString *dateStr = @"Sat Sep 15 05:52:10 +0000 2012";

NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"EE LLLL d HH:mm:ss Z yyyy"];
NSDate *date = [dateFormat dateFromString:dateStr];