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#include <stdio.h> #include <stdlib.h> typedef struct { int num; char *name; char sex; float score; } STU; int main() { int i; STU Student0; /* a STU variable */ STU * Student1 = NULL; /* a pointer to a STU variable */ STU * Student2 = NULL; /* a pointer to a 1D STU array */ STU ** Student3 = NULL; /* a pointer to a pointer to STU variable */ STU ** Student4 = NULL; /* a pointer to a 2D STU array */ /* initialize STUDENT0 */ Student0.num=122; Student0.name= "zhang ping"; Student0.sex='M'; Student0.score=99.2; /* can't use Student0={102,"Zhang ping",'M',78.5} You can use STU Student0={102,"Zhang ping",'M',78.5} */; /* a pointer to a STU variable */ Student1=&Student0; /* a pointer to a 1D STU array (1*3)*/ Student2 = (STU *) calloc(3, sizeof(STU)); /* a pointer to a pointer to STU variable */ Student3=&Student1; /* a pointer to to a 2D STU array (3*3) */ Student4 = (STU **) calloc(3, sizeof(STU *)); for (i=0; i<3; i++) { Student4[i] = (STU *) calloc(3, sizeof(STU)); } Student1->num=2; Student1->name= "zhang ling2"; (*Student1).sex='f'; (*Student1).score=99.2; /*(col 2) allocate value */ (Student2+1)->num=3; (*(Student2+1)).name="zhang cai"; Student2[1].sex='f'; Student2[1].score=99.5; (*Student3)->num=4; (*Student3)->name= "zhang ling4"; (**Student3).sex='m'; (**Student3).score=99.3; /* (col 3 row 2) allocate value */ Student4[2][1].num=5; Student4[2][1].name="zhang cai2"; Student4[2][1].sex='f'; Student4[2][1].score=99.6; /* Free memory */ free(Student1); free(Student2); free(Student3); free(Student4); return 0; } |