Ichaza ukuthi umhleli we-C udala, alivule futhi alivale kanjani ifayela lombhalo, noma ifayela kanambambili.
Ifayela, lisho uchungechunge lwamabhayithi, kungakhathaliseki ukuthi ifayela lombhalo noma ifayela kanambambili, C Ulimi, alihlinzeki nje ngokufinyelela kumisebenzi yezinga eliphezulu, kodwa futhi linikeza ucingo oluyisisekelo (i-OS) lokucubungula amafayela kudivayisi yokugcina. .Lesi sahluko sizochaza izingcingo ezibalulekile ekuphathweni kwemibhalo.
vula ifayela
Ngokuvamile kusetshenziswa umsebenzi we-fopen () ukuze udale ifayela elisha noma uvule ifayela elikhona kakade, le kholi iqalisa into yohlobo lwe-FILE equkethe lonke ulwazi oludingekayo ukuze ulawule ukugeleza.Nasi isibonelo salolu hlelo lokusebenza:
FILE *fopen ( const char * filename , const char * mode );
Lapha igama lefayela liwuchungechunge lokuqamba ifayela, inani lemodi yokufinyelela lingaba elinye lamanani alandelayo:
| iphethini | incazelo |
| r | Vula ifayela lombhalo elikhona elivumela ukuthi lifundwe. |
| w | Vula ifayela lombhalo elivumela ukubhala kufayela.Uma ifayela lingekho, ifayela elisha liyakhiwa.Lapha, uhlelo lwakho lubhala okuqukethwe kusukela ekuqaleni kwefayela.Uma ifayela likhona, lizoncishiswa libe nguziro ubude futhi libhalwe kabusha. |
| a | Vula ifayela lombhalo bese ubhalela ifayela kumodi ye-append.Uma ifayela lingekho, ifayela elisha liyakhiwa.Lapha, uhlelo lwakho lwengeza okuqukethwe kumafayela osuvele unawo. |
| r+ | Vula ifayela lombhalo elikuvumela ukuthi ufunde futhi ubhale ifayela. |
| w+ | Vula ifayela lombhalo elikuvumela ukuthi ufunde futhi ubhale ifayela.Uma ifayela selivele likhona, ifayela liyancishiswa libe nguziro ubude, futhi uma ifayela lingekho, kwakhiwa ifayela elisha. |
| a+ | Vula ifayela lombhalo elikuvumela ukuthi ufunde futhi ubhale ifayela.Uma ifayela lingekho, ifayela elisha liyakhiwa.Ukufundwa kuqala ekuqaleni kwefayela, futhi ukubhala kumodi yokufaka kuphela. |
Uma licutshungulwe ifayela kanambambili, sebenzisa imodi yokufinyelela elandelayo ukuze umiselele okungenhla:
"rb", "wb", "ab", "rb+", "r+b", "wb+", "w+b", "ab+", "a+b"
ifayela elivaliwe
Ukuvala ifayela, sicela usebenzise umsebenzi we-fclose().I-prototype yomsebenzi imi kanje:
int fclose ( FILE * fp );
- Uma ifayela livaliwe ngempumelelo, umsebenzi we-fclose() ubuyisela uziro, futhi uma iphutha libuyisela i-EOF.Lo msebenzi, empeleni, ususa idatha ku-buffer, uvala ifayela, futhi ukhiphe yonke inkumbulo esetshenziselwa lelo fayela.I-EOF ichazwa njalo kunhlokweni yefayela elithi stdio.h
Umtapo wezincwadi ojwayelekile we-C uhlinzeka ngemisebenzi ehlukahlukene yokufunda nokubhala amafayela ngezinhlamvu noma njengeyunithi yezinhlamvu yobude obugxilile.
Bhala efayeleni
Nansi imisebenzi elula yokubhala izinhlamvu ekusakazweni:
int fputc (int c, FILE *fp);
Umsebenzi fputc () ubhala inani lohlamvu lwepharamitha c emfudlaneni okukhiphayo i-fp ekhomba kukho.Uma ukubhala kuphumelele, kubuyisela uhlamvu olubhaliwe kanye ne-EOF uma kwenzeka iphutha.Ungasebenzisa umsebenzi olandelayo ukuze ubhale iyunithi yezinhlamvu egcina ngokungenalutho ekusakazweni:
int fputs ( const char *s , FILE *fp );
Umsebenzi othi fputs () ubhala iyunithi yezinhlamvu s emfudlaneni ophumayo lapho i-fp ikhomba khona.Uma ukubhala kuphumelela, kubuyisela inani elingelona inegethivu kanye ne-EOF uma kwenzeka iphutha.Ungasebenzisa futhi umsebenzi we-int fprintf (FILE * fp, const char * format,...) ibhala iyunithi yezinhlamvu efayeleni.Zama isibonelo esilandelayo:
Qaphela:Qiniseka ukuthi unohla lwemibhalo olutholakalayo lwe-tmp, futhi uma lungekho, udinga ukulwenza kukhompuyutha yakho kuqala.
/ tmp ngokuvamile uhla lwemibhalo lwesikhashana ohlelweni lwe-Linux.Uma usebenzisa uhlelo lwe-Windows, udinga ukuluguqulela kuhla lwemibhalo olukhona endaweni yendawo, njenge: C: \ tmp, D: \ tmp, njll.
isibonelo esiphilayo
#fakaint main () {IFILE *fp = NULL;fp = fopen ("/tmp/test.txt ", "w+");fprintf (fp , "Lokhu ukuhlola i-fprintf...\n ");fputs ("Lokhu ukuhlola ama-fputs...\n ", fp );ukuvala (fp);}
Uma ikhodi engenhla ihlanganiswa futhi isetshenziswa, idala ifayela elisha elithi test.txt inthe/tmp directory.Futhi ubhalela imigqa emibili esebenzisa imisebenzi emibili ehlukene.Asifunde leli fayela ngokulandelayo.
Funda ifayela
Okulandelayo umsebenzi olula kakhulu wokufunda uhlamvu olulodwa efayelini:
int fgetc (IFILE * fp);
Umsebenzi we-fgetc () ufunda uhlamvu efayelini lokufaka lapho i-fp ikhomba khona.Inani lokubuyisela uhlamvu olufundiwe kanye ne-EOF uma kwenzeka iphutha.Umsebenzi olandelayo ukuvumela ukuthi ufunde iyunithi yezinhlamvu ephuma emfudlaneni:
char *fgets ( char *buf , int n , FILE *fp );
I-function fgets () ifunda izinhlamvu ze-n-1 kusukela ekusakazeni kokufaka okuqondiswa yi-fp.Ikopisha iyunithi yezinhlamvu efundiwe kubhafa bese yengeza uhlamvu olungenalutho ekugcineni ukuze inqamule uchungechunge.
Uma lo msebenzi uhlangabezana nohlamvu lomugqa ophukile '\ n' noma i-EOF yokuphela kwefayela ngaphambi kokufunda uhlamvu lokugcina, bese ubuyiselwa kuphela ezinhlamvu ezifundiwe, okuhlanganisa ukuhlukana kwemigqa.Ungasebenzisa futhi umsebenzi we-int fscanf (FILE * fp, const char * format,...) ukuze ufunde iyunithi yezinhlamvu efayelini, kodwa iyeke ukufunda lapho ihlangabezana nesikhala sokuqala nokugqashuka komugqa.
isibonelo esiphilayo
#fakaint main () {IFILE *fp = NULL;i-char buff [255];fp = fopen ("/tmp/test.txt ", "r");fscanf (fp , "%s", buff );printf ("1: %s \n ", buff );fgets (buff , 255, (IFILE *)fp);printf ("2: %s \n ", buff );fgets (buff , 255, (IFILE *)fp);printf ("3: %s \n ", buff );ukuvala (fp);}
Lapho ikhodi engenhla ihlanganiswa futhi isetshenziswa, ifunda amafayela adalwe esigabeni esedlule, ikhiqize imiphumela elandelayo:
1: Le 2: ihlola i-fprintf...
3: Lokhu ukuhlola ama-fputs...
Okokuqala, indlela ye-fscanf() ifunda kuphela Lokhu .ngoba ihlangabezana nesikhala ngemuva.Okwesibili, shayela i-functon fgets () ukuze ufunde ingxenye esele kuze kube sekupheleni komugqa.Ekugcineni, shayela ama-fgets () ukuze ufunde umugqa wesibili ngokuphelele.
Kanambambili I / O umsebenzi
Imisebenzi emibili elandelayo isetshenziselwa okokufaka nokukhiphayo kanambambili:
size_t fread (okungenalutho *ptr , size_t size_of_elements, size_t number_of_elements, FILE *ifayela);size_t fwrite (const void *ptr , size_t size_of_elements , size_t number_of_elements , FILE *a_file );
Yomibili imisebenzi iyafundwa futhi ibhalelwe amabhulokhi esitoreji-imvamisa ama-arrays noma izakhiwo.
Ngaphezulu mayelana nokufundwa kwefayela nokubhala kwe-C kungokwe-HDV Phoelectron Technology Ltd., umsebenzi wobuchwepheshe wesofthiwe.Nenkampani yemishini ehlobene nenethiwekhi (njenge: ACI-ONU/ ukuxhumanaI-ONU/ ehlakaniphileI-ONU/ fiberI-ONU, njll.) ihlanganise ithimba lesofthiwe elinamandla, ikhasimende ngalinye lenza ngendlela oyifisayo izimfuno ezikhethekile elizidingayo, futhi livumele imikhiqizo yethu ihlakaniphe futhi ithuthuke kakhulu.