Con tro trong C

by **dathl_c00493** Mon Dec 27, 2010 2:05 am

Day la mot trong so nhung phan kho cua C.
Vi con tro la 1 cong cu qua linh hoat, nen doi khi khai niem con tro gay chut it nham lan cho chung ta.

by **dathl_c00493** Mon Dec 27, 2010 2:15 am

Code:: /*nhap gia tri cua 2 bien a, b bang con tro hoan doi gia tri & dia chi cua a, b bang con tro ket qua: hien thi gia tri & dia chi cua 2 bien a, b sau khi hoan doi*/ #include<stdio.h> int main(){ int a, b; int *p1, *p2, *pTem; p1 = &a; p2 = &b; printf("a = "); scanf("%d", p1); printf("\nb = "); scanf("%d", p2); printf("\ntruoc khi doi cho: "); printf("\ndia chi cua a = %d la %X\n", *p1, p1); printf("dia chi cua b = %d la %X \n", *p2, p2); // hoan vi a, b dung chi so pTem = p1; p1 = p2; p2 = pTem; printf("\nsau khi doi cho: "); printf("\ndia chi cua a = %d la %X\n", *p1, p1); printf("dia chi cua b = %d la %X \n", *p2, p2); fflush(stdin); getchar(); }

by **dathl_c00493** Mon Dec 27, 2010 2:16 am

Code:: /*nhap du lieu cho mang Arr thong qua con tro ptr hien thi mang bang con tro mang(ten cua mang) */ #include<stdio.h> int main(){ int n, i; printf("nhap vao so phan tu cua mang: n = "); scanf("%d", &n); float Arr[n]; float *ptr; // nhap du lieu cho mang ptr = Arr; for(i = 0; i < n; i++){ printf("nhap so thu %d: ", i + 1); scanf("%f", ptr + i); } //hien thi mang printf("\nmang:"); for(i = 0; i < n; i++){ printf("%-5.2f", *(Arr + i)); } fflush(stdin); getchar(); }

by **dathl_c00493** Mon Dec 27, 2010 2:17 am

Code:: /* nhap du lieu cho 2 mang A, B dung con tro de tinh toan va hien thi mang C[i] = A[i] + B[i] */ #include<stdio.h> int main(){ int A[5], B[5]; int C[5]; int *pA, *pB,*pC; int i; // nhap mang A dung con tro pA pA = A; for(i = 0; i < 5; i++ ){ printf("phan tu thu %d cua A: ", i + 1); scanf("%d", pA + i); } printf("\n"); // nhap mang B dung con tro pB pB = B; for(i = 0; i < 5; i++ ){ printf("phan tu thu %d cua B: ", i+1); scanf("%d", pB + i); } // tinh tong 2 mang va hien thi mang C dung con tro pC pC = C; for(i = 0; i < 5; i++){ *(pC + i) = *(pA + i) + *(pB +i); } printf("\nmang C: "); for(i = 0; i < 5; i++){ printf("%-5d", *(pC + i)); } fflush(stdin); getchar(); }

by **dathl_c00493** Mon Dec 27, 2010 2:19 am

Code:: /*dung con tro cap phat bo nho dong cho mang */ #include<stdio.h> int main(){ int n; printf("nhap vao so phan tu cua mang: "); scanf("%d", &n); int *ptr; ptr = (int*)malloc(n * sizeof(int)); //tuong duong voi khai bao ptr[n] voi n phan tu kieu int int i; for(i = 0; i < n; i++){ printf("nhap phan tu thu %d cua mang: ", i + 1); scanf("%d", &ptr[i]); } printf("\nhien thi mang vua nhap: "); for(i = 0; i < n; i++){ printf("%-5d", ptr[i]); } printf("\ncac so nguyen to trong mang: "); i = 0; do{ int j, count = 0; for(j = 2; j <=sqrt(ptr[i]); j++ ){ if(ptr[i] % j == 0) count++; } if(ptr[i] < 2) i++; else{ if(count == 0){ printf("%-5d", ptr[i]); } i++; } }while(i < n); free(ptr); fflush(stdin); getchar(); }