c 関数 'strcpy' に問題があり、それを理解できませんでした。
これには、Argv のような char *[] へのコピーが含まれます (ただし、実際には Argv ではありません)。構造体からコピーすることはできますが、中にコピーすることはできません。ただし、Argv 構造体全体を最初に 1 回で宣言した場合に限ります。
char *[]
aは であり、 の配列であると仮定しchar*
ます。
この問題の簡単なデモ プログラムを次に示します。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
char FN[]="BBBB";
char *TL[]={
"a0 ",
"a1 ",
"a2 ",
"a3 ",
"a4 ",
"a5 "};
char BN[]="c1 ";
char N0[]="N0 ";
char N1[]="N1 ";
char N2[]="N2 ";
char N3[]="N3 ";
char N4[]="N4 ";
char N5[]="N5 ";
char* TD[6];
int main ( int argc, char *argv[] )
{
// FN is a pointer to an array of chars
// BN is the same
//TL is an array of pointers (that each point to an array of chars)
//TL[1] is thus a pointer to an array of chars
//TL is the same structure as Argv
//TD is the same structure as Argv (but built up from parts)
// but is spread out across the globals and the main func.
// thus less easy to read and understand then TL.
//TL[i], TD[i], and BN are initially allocated significantly larger than FN
// to remove the worry of overruns.
//copy "a1 \0" into the space held by "c1 "
strcpy(BN,TL[1]); //works
//copy "BBBB\0" into the space held by "c1 "
strcpy(BN,FN); //works
TD[0]=N0;
TD[1]=N1;
TD[2]=N2;
TD[3]=N3;
TD[4]=N4;
TD[5]=N5;
//copy "BBBB\0" into the space held by "a1 "
strcpy(TD[1],FN); //works
//copy "BBBB\0" into the space held by "a1 "
//strcpy(TL[1],FN); //dies
}