An warware: za mu iya rubuta shirin ba tare da main a c

Da farko, a matsayina na ƙwararren mai haɓakawa da ke da zurfin ilimi a cikin shirye-shiryen C, an yi mini tambaya akai-akai game da ko zai yiwu a rubuta shirin a cikin C ba tare da amfani da babban aikin ba. Amsar ita ce, eh, yana yiwuwa kuma zan yi bayanin yadda wannan ke aiki. Wasu masu haɗawa kamar GCC, suna ba da damar wannan, kuma yana da ban sha'awa a cikin sassauƙa da yuwuwar shirye-shiryen C. Koyaya, ana ɗaukar wannan motsi ba daidai ba ne. To me yasa wannan sha'awar ta taso? Domin a al'adance, an ce aiwatar da shirin C yana farawa daga babban aikin. Wannan gaskiya ne kuma yana aiki daidai ga mafi yawan ma'auni.

Aikin _start()

Mafarin farawa na ainihi a yawancin shirye-shiryen C shine ainihin aiki da ake kira _start(). Yawancin lokaci, wannan aikin bootstrap ne wanda ke fara samar da albarkatun da ake buƙata kuma a ƙarshe ya kira babban (). An shigar da aikin _start() a cikin shirin C ta mai tarawa, dabam da lambar tushen ku. Saboda haka, ya riga ya wanzu kuma yana yin aikinsa a asirce a bayan fage ba tare da yawancin masu haɓakawa suna buƙatar saninsa ba.

Amfani da _start () a wurin babban()

Sirrin ra'ayi na gudanar da shirin C ba tare da babban() yana tare da kawo wannan ba _start () aiki a cikin fage kuma yadda ya kamata amfani da shi a madadin main(). Wannan ita ce dabarar da masu tara GCC ke ba mu damar yi. Ga yadda:

void _start() {
     // Add your code here
    _exit(0);
}

Kula da amfani da aikin _exit() a ƙarshen. Wannan yana da mahimmanci saboda idan shirin bai kira _exit() ba, shirin zai fadi.

Fahimtar Gudun Shirin

Wannan shi ne yadda shirin zai yi aiki: A daidaitattun shirye-shiryen C, aikin _start () wanda mai tarawa ya samar, zai kira babban () aikin. Koyaya, a wannan yanayin, mun maye gurbin babban () aikin da namu _start (), kuma yana aiwatarwa kai tsaye maimakon kiran main(). Ayyukan _exit() kira ne na tsarin da zai ƙare shirin mu daidai.

Bayanan kula akan Dogaran Laburare

• Duk da yake yana da ban sha'awa don ƙididdige shirin C ba tare da babban() ba, akwai ƴan koma baya. Wannan aikin yana gabatar da adadi mai kyau dogaro da ɗakin karatu cikin code din ku. Misali, don amfani da aikin _exit(), ɗakin karatu na unistd.h ya zama dole.
• Wannan bazai zama matsala da farko ba, amma idan kuna tsammanin lambar ku ta gudana akan tsari da mahalli daban-daban, ana ba da shawarar ku tsaya tare da babban aikin () saboda yana kawo babban matakin ɗaukar nauyi.

A ƙarshe, mun ga yadda zai yiwu a ƙirƙira wani shiri na musamman na C wanda ke gudana ba tare da babban aikin () ba. Wannan shaida ce ga sassauƙar harshe na C. Yana da mahimmanci, duk da haka, a lura cewa wannan al'ada ba ta dace ba, don haka amfani da hankali.