qt - Is this usage of arg ok? -

msg.append(qstring("\"settime\": %1000,")  .arg(eventlist[i].failurebegin)); // set time 

i know if it`s ok have %1 right next 000. since there 1 argument there no confusion possible qstring if had 10 .arg() confuse %10 right? there escape sequence or have break down concatenations?

it not ok. can explore source code of qstring::arg or let me show you.

qstring qstring::arg(qlonglong a, int fieldwidth, int base, qchar fillchar) const {     argescapedata d = findargescapes(*this);     if (d.occurrences == 0) {         qwarning() << ""qstring::arg: argument missing:"" << *this << ',' << a;         return *this;     }     //.... not important. } 

this how findargescapes implemented. think source code of qt more readable stl implementations.

static argescapedata findargescapes(const qstring &s) {     const qchar *uc_begin = s.unicode();     const qchar *uc_end = uc_begin + s.length();     argescapedata d;     d.min_escape = int_max;     d.occurrences = 0;     d.escape_len = 0;     d.locale_occurrences = 0;     const qchar *c = uc_begin;     while (c != uc_end) {         while (c != uc_end && c->unicode() != '%')             ++c;         if (c == uc_end)             break;         const qchar *escape_start = c;         if (++c == uc_end)             break;         bool locale_arg = false;         if (c->unicode() == 'l') {             locale_arg = true;             if (++c == uc_end)                 break;         }          int escape = c->digitvalue();         if (escape == -1)             continue;         ++c;         if (c != uc_end) {             int next_escape = c->digitvalue();             if (next_escape != -1) {                 escape = (10 * escape) + next_escape;  //*************                 ++c;             }         }         if (escape > d.min_escape)             continue;         if (escape < d.min_escape) {             d.min_escape = escape;             d.occurrences = 0;             d.escape_len = 0;             d.locale_occurrences = 0;         }         ++d.occurrences;         if (locale_arg)             ++d.locale_occurrences;         d.escape_len += c - escape_start;     }     return d; }