char color5 red blue yellow green black red

指针数组 char * color[5] = { “red”, “blue”, “yellow”, “green”, “black” red color[0 0 }; blue ]color[1 ]color[2 ]color[3 ]color[4 ] 3 0 yellow 0 green 0 black 0

指针数组 char * color[5] = { “red”, “blue”, “yellow”, “green”, “black” red color[0 }; 0 blue ]color[1 ]color[2 ]color[3 ]color[4 ] for( i=0; i<5; i++ ) printf("%d-th color = %sn", i, 5 0 yellow 0 green 0 black 0

指针数组 char * color[5] = { “red”, “blue”, “yellow”, “green”, “black” red }; color[0 ]color[1 ]color[2 ]color[3 ]color[4 ] char *t = color[0]; color[0] = color[4]; color[4] = t; 对一般数组的操作，适合于指针数组 定义，初始化，元素的使用，赋值 6 0 blue 0 yellow 0 green 0 black 0

指针数组和二级指针 char * color[5] = { “red”, “blue”, “yellow”, “green”, “black” color[0 }; color ]color[1 ]color[2 ]color[3 ]color[4 ] 数组名color是一指针， 指向首元素color[0]。 char **pc = color; pc char str[20]; scanf(“%s”, str); for ( i=0; i<5; i++ ) pc[i] if( strcmp(str, *(pc+i))==0 ) break; if(i<5) printf(“color id = %dn”, i); else printf(“not foundn”); 10 red 0 blue 0 yellow 0 green 0 black 0

11. 1. 4 指针数组与二维数组 red ccolor r e d b l u r y e l l o w g r e e n b l a c k pcolor[ 0] pcolor[ 1] 2] pcolor[ 3] pcolor[ 4] char ccolor[][7] = { “red”, “blue”, “yellow”, “green”, “black” }; char * pcolor[5] = { “red”, “blue”, “yellow”, “green”, “black” }; 0 blue 0 yellow 0 green 0 black 0

11. 1. 4 指针数组与二维数组 red ccolor r e d b l u r y e l l o w g r e e n b l a c k pcolor[ 0] pcolor[ 1] 2] pcolor[ 3] pcolor[ 4] 0 blue 0 yellow 0 green 0 black 0 pcolor[i]指向一个字符串，即该字符串首个字符 pcolor[i] + k 则指向该字符串的第k个字符 所以 *(pcolor[i] + k)就是该字符，也可以写作 pcolor[i][k] 注意：pcolor不是二维数组

[例11 -4] 字符串排序 #define SWAP(a, b, t) t=a, a=b, b=t void fsort(char* color[], int n) { int k, j; char * tmp; for( k=1; k<n; k++ ) for( j=0; j<n-k; j++ ) if( strcmp(color[j], color[j+1])>0 ) SWAP (color[j], color[j+1], tmp); }

pcolor[ 0] pcolor[ 主程序 pcolor[ 1] 2] pcolor[ void main() 3] pcolor[ { 4] char *pcolor[5]={“red”, blue”, “yellow”, “green”, “black”}; int k; fsort(pcolor, 5); for( k=0; k<5; k++ ) printf(“%s”, pcolor[k]); } red 0 blue 0 yellow 0 green 0 black 0

11. 2 字符定位（错误） char * match(char ch) { char str[] = “university”; char * s = str; while (*s) if( *s==ch ) return s; else s++; return NULL; } void main() { char * r; r = match(‘v’); if( r ) printf(“%s”, r); } 返回的指针不合法！！

11. 2. 3 函数指针作为参数 /* 用梯形公式计算一个函数的积分 */ double calc(double (*fp)(double), double a, double b) { double z; z = (b-a)/2 * (fp(a)+fp(b)); return z; }

11. 2. 3 函数指针作为参数 double f 1(double x) { return x*x; } double f 2(double x) { return sin(x)/x; } void main() { double result; double (*fp)(double); fp = f 1; result = calc(fp, 1, 2); result = calc(f 2, 1, 2); }