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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <string.h>
  4.  
  5. #define MAX_SRC_LEN 20
  6. #define MAX_DUP_NUM 4
  7.  
  8. #define TO_TEXT(A) #A
  9. #define BUILD_FORMAT(LEN) "%" TO_TEXT(LEN) "s"
  10. #define INPUT_FORMAT BUILD_FORMAT(MAX_SRC_LEN)
  11.  
  12. char *copyStr(int n, const char *str);
  13.  
  14. static inline
  15. void clearStdinBuf()
  16. {
  17.     char c;
  18.     while((c = getchar()) != '\n' && c != EOF);
  19. }
  20.  
  21. int main(void) {
  22.     char srcStr[MAX_SRC_LEN + 1] = {0}; // +1 for '\0'
  23.     char *dupStr;
  24.     int n, ret;
  25.  
  26.     printf("using format for scanf: %s\n", INPUT_FORMAT);
  27.     printf("enter a string(len<=%d):", MAX_SRC_LEN);
  28.     ret = scanf(INPUT_FORMAT, srcStr);
  29.     if (ret <= 0) {
  30.         printf("error on scanf\n");
  31.         return 1;
  32.     }
  33.     // clear extra input
  34.     if (strlen(srcStr) == MAX_SRC_LEN) clearStdinBuf();
  35.  
  36.     printf("n(n<=4)=");
  37.     do {
  38.         ret = scanf("%d", &n);
  39.         if (ret <= 0) clearStdinBuf();
  40.         if (n > 0 && n <= 4) break;
  41.         printf("the n must <= 4, got %d, please enter again:", n);
  42.     } while (1);
  43.  
  44.     dupStr = copyStr(n, srcStr);
  45.     printf("%s\n", dupStr);
  46.  
  47.     return 0;
  48. }
  49.  
  50. char *copyStr(int n, const char *str) {
  51.     int i, j, len = strlen(str);
  52.     static char array[MAX_SRC_LEN * MAX_DUP_NUM + 1]; // +1 for '\0'
  53.     for (i = 0; i < n; i++) {
  54.         for (j = 0; j < len; j++) {
  55.             array[len * i + j] = str[j];
  56.         }
  57.     }
  58.     array[len * i] = '\0';
  59.     return array;
  60. }
  61.  
Success #stdin #stdout 0s 2164KB
comments (?)
stdin
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asdfg
2
stdout
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using format for scanf: %20s
enter a string(len<=20):n(n<=4)=asdfgasdfg
https://ideone.com/R5uZx7
language:
C (gcc 8.3)
created:
9 years ago
visibility:
public

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