C程序，功能如題，代碼如下：

/*功能：輸出一個文件的最后n行數據，如果文件總行數不足n行，則顯示全部數據基本思路：產生一個長度為n的二維數組，將它作為一個循環隊列來看待 */#include <stdio.h> #include <stdlib.h> #include <string.h>#define BUFLEN 256// 顯示一個文件的最后len行數據 void run(char *filename, int len) {int i;char **buf = NULL;char temp[BUFLEN] = {0};FILE *fp;buf = malloc(len * sizeof(char*));for(i = 0; i < len; i++){buf[i] = (char*)malloc(BUFLEN * sizeof(char));memset(buf[i], 0, BUFLEN * sizeof(char)); // 清零}if((fp = fopen(filename, "r")) == NULL){printf("open file [%s] failed\n", filename);}else{i = 0;int lineCount = 0; // 文件的實際行數while(fgets(temp, BUFLEN, fp) != NULL){strcpy(buf[i], temp);i = (i + 1) % len; lineCount++; // 數據行數加1}printf("lineCount = %d\n", lineCount);if(lineCount <= len) // 文件實際行數小于等于需要提取的行數{for(i = 0; i < lineCount; i++)printf("L%d: %s", i+1, buf[i]);}else{int start = i;do {printf("L%d: %s", i, buf[i]);i = (i + 1 + len) % len;} while (i != start);}}fclose(fp);for(i = 0; i < len; i++)free(buf[i]);free(buf); }int main(int argc, char *argv[]) {if(argc < 3){printf("Usage: %s <filename> <n>\n", argv[0]);}else{int n = atoi(argv[2]);run(argv[1], n);printf("\n");}return 0; }

運行結果：

[zcm@t #93]$./a test2.txt 2 lineCount = 4 L0: 3 chinese Chinese environment L1: 4 english English environment [zcm@t #94]$./a test2.txt 5 lineCount = 4 L1:  1 come one, obay L2: 2 <Quidway> language-mode ? L3: 3 chinese Chinese environment L4: 4 english English environment [zcm@t #95]$./a test2.txt 4 lineCount = 4 L1:  1 come one, obay L2: 2 <Quidway> language-mode ? L3: 3 chinese Chinese environment L4: 4 english English environment [zcm@t #96]$./a test2.txt 3 lineCount = 4 L1: 2 <Quidway> language-mode ? L2: 3 chinese Chinese environment L0: 4 english English environment [zcm@t #97]$

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總結

以上是生活随笔為你收集整理的输出一个文件的最后n行数据，如果文件总行数不足n行，则显示全部数据的全部內容，希望文章能夠幫你解決所遇到的問題。

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