comment récuperer la date d'hier

bonjour

je veux récuperer la date J-1 j'ai trouvé ce code

Code:

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char dateheure[12]; //buffer contenant la chaîne finale time_t time_of_day; //valeur contenant le temps écoulé en secondes depuis 01/01/1970 time_of_day = time( 1 ); //récupère le temps passé strftime(dateheure, 12, "%d%m%y", localtime(&time_of_day));

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mais il récuper que la date du jour

merci

Deux solution
La première retirer 24h au resultat de time (60*60*24)

La seconde:
si tu regarde le man de localtime tu verra qu'il te retourne une structure avec toutes les information nécessaire à l'intérieur.

Ensuite il suffit de faire -1 au bons endroit pour obtenir la date d'hier.

Citation:

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struct tm *localtime(const time_t *timep);

Description

The ctime(), gmtime() and localtime() functions all take an argument of data type time_t which represents calendar time. When interpreted as an absolute time value, it represents the number of seconds elapsed since 00:00:00 on January 1, 1970, Coordinated Universal Time (UTC).

The asctime() and mktime() functions both take an argument representing broken-down time which is a representation separated into year, month, day, etc.

Broken-down time is stored in the structure tm which is defined in <time.h> as follows:

struct tm {
int tm_sec; /* seconds */
int tm_min; /* minutes */
int tm_hour; /* hours */
int tm_mday; /* day of the month */
int tm_mon; /* month */
int tm_year; /* year */
int tm_wday; /* day of the week */
int tm_yday; /* day in the year */
int tm_isdst; /* daylight saving time */
};

The members of the tm structure are:

• tm_sec
  The number of seconds after the minute, normally in the range 0 to 59, but can be up to 60 to allow for leap seconds.
• tm_min
  The number of minutes after the hour, in the range 0 to 59.
• tm_hour
  The number of hours past midnight, in the range 0 to 23.
• tm_mday
  The day of the month, in the range 1 to 31.
• tm_mon
  The number of months since January, in the range 0 to 11.
• tm_year
  The number of years since 1900.
• tm_wday
  The number of days since Sunday, in the range 0 to 6.
• tm_yday
  The number of days since January 1, in the range 0 to 365.
• tm_isdst
  A flag that indicates whether daylight saving time is in effect at the time described. The value is positive if daylight saving time is in effect, zero if it is not, and negative if the information is not available.

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Pour éviter les problèmes de changement de mois ou d'année je prendrais le timestamp auquel je retrancherais 86400 (nombre de secondes dans une journée)

puis t'as juste a convertir le résultat en date